fix: Enabling plugins + destinations gating

[tiina303]

Problem

Enabling plugins was broken because enabled was pulled out of the formData, so if was always added as false. Destinations weren't gated by data-pipelines add-on

Changes

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Does this work well for both Cloud and self-hosted?

How did you test this code?

Verified that I can now enable/disable plugins. Destinations creation pages showed upgrade option and toggles as well.

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 1)
• webkit: 0 added, 0 modified, 0 deleted

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[github-actions[bot]]

Size Change: 0 B

Total Size: 1.05 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	1.05 MB

_{compressed-size-action}

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 1)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.