stats: add tag extraction rules for ADS disconnections

[grnmeira]

Commit Message: adds tag extraction rules for envoy.ads_cluster.streams_closed. Additional Description: as seen on #21595 Risk Level: low Testing: removes skip_tag_extraction_rule_check_ from ADS integration tests. Docs Changes: Release Notes: Platform Specific Features: [Optional Runtime guard:] [Optional Fixes #Issue] [Optional Fixes commit #PR or SHA] [Optional Deprecated:] [Optional API Considerations:]

[tyxia]

Maybe @adisuissa can help to review this PR, as xDS expert.

[adisuissa]

/wait

[grnmeira]

@adisuissa please let me know if you're happy with my changes. All CI checks passing now.

[KBaichoo]

friendly ping @adisuissa . PTAL