[gha] update compat image to testnet prefix

[rustielin]

Description

use the testnet_ -prefixed release image

Test Plan

---

This change is 

[davidiw]

should we just make this the latest testnet or would that be too flaky?

[rustielin]

There was concern that latest testnet would be confusing since it's a mutable image tag. If we were to push testnet branch (and push the image) at the same time as a test, it would be difficult to know the exact commit hash we're testing against. Better to be explicit with the commit hash -- and also since we're expected to be always backwards compat, this should always work @davidiw

[github-actions[bot]]

Forge is running suite land_blocking on 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

• Grafana dashboard (auto-refresh)
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

Forge is running suite compat on testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

• Grafana dashboard (auto-refresh)
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

Forge is running suite compat on 2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

• Grafana dashboard (auto-refresh)
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

Forge is running suite land_blocking on 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

• Grafana dashboard (auto-refresh)
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

:white_check_mark: Forge suite compat success on 2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

Compatibility test results for 2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2 (PR)
1. Check liveness of validators at old version: 2d8b1b57553d869190f61df1aaf7f31a8fc19a7b
compatibility::simple-validator-upgrade::liveness-check : 7610 TPS, 5097 ms latency, 7100 ms p99 latency,no expired txns
2. Upgrading first Validator to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::single-validator-upgrade : 4972 TPS, 8380 ms latency, 10900 ms p99 latency,no expired txns
3. Upgrading rest of first batch to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::half-validator-upgrade : 4681 TPS, 8738 ms latency, 10900 ms p99 latency,no expired txns
4. upgrading second batch to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::rest-validator-upgrade : 6629 TPS, 5813 ms latency, 9700 ms p99 latency,no expired txns
5. check swarm health
Compatibility test for 2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2 passed
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

:white_check_mark: Forge suite land_blocking success on 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

performance benchmark with full nodes : 6694 TPS, 5931 ms latency, 25800 ms p99 latency,(!) expired 2616 out of 2861280 txns
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

:white_check_mark: Forge suite land_blocking success on 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

performance benchmark with full nodes : 6661 TPS, 5966 ms latency, 8100 ms p99 latency,no expired txns
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions[bot]]

:white_check_mark: Forge suite compat success on testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2

Compatibility test results for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2 (PR)
1. Check liveness of validators at old version: testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b
compatibility::simple-validator-upgrade::liveness-check : 7566 TPS, 5125 ms latency, 6900 ms p99 latency,no expired txns
2. Upgrading first Validator to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::single-validator-upgrade : 4936 TPS, 8432 ms latency, 10700 ms p99 latency,no expired txns
3. Upgrading rest of first batch to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::half-validator-upgrade : 4346 TPS, 9569 ms latency, 13000 ms p99 latency,no expired txns
4. upgrading second batch to new version: 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2
compatibility::simple-validator-upgrade::rest-validator-upgrade : 6556 TPS, 5747 ms latency, 10900 ms p99 latency,no expired txns
5. check swarm health
Compatibility test for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> 8a3d1a33f16af55e7c3a5b117015a7a131c0ffc2 passed
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[msmouse]

yeah I feel safer knowing it's compatible with an even older tag than a small increment.