Allow configuring Sentry taskworker concurrency via env

[madest92]

It replaces the hardcoded --concurrency value in docker-compose.yml with SENTRY_TASKWORKER_CONCURRENCY, improving flexibility for different deployment sizes while preserving the existing default.

[aminvakil]

Thank you for this.

Also for future reference, this is the PR which implemented concurrency in taskworker:

getsentry/sentry#83254

As @markstory has said in PR:

This will help enable higher CPU usage in worker pods, as we can pack more concurrent CPU operations into each pod (at the cost of memory).

And @aldy505 had a discussion about this number in https://github.com/getsentry/self-hosted/pull/3738/changes#r2133139080 which I'm adding here for reference as well.

[markstory]

Makes sense to me.

[github-actions]

Semver Impact of This PR

⚪ None (no version bump detected)

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Internal Changes 🔧

Deps

• Bump actions/checkout from 6.0.0 to 6.0.2 by dependabot in #4155
• Bump actions/setup-python from 6.1.0 to 6.2.0 by dependabot in #4154
• Bump getsentry/craft from 2.19.0 to 2.20.1 by dependabot in #4152
• Bump actions/setup-node from 6.1.0 to 6.2.0 by dependabot in #4153
• Bump astral-sh/setup-uv from 7.1.6 to 7.2.0 by dependabot in #4132
• Bump codecov/test-results-action from 1.1.1 to 1.2.1 by dependabot in #4115
• Bump codecov/codecov-action from 5.5.1 to 5.5.2 by dependabot in #4102
• Bump urllib3 from 2.5.0 to 2.6.3 by dependabot in #4150

Other

• Fix changelog-preview for external contributors by BYK in #4158

Other

• Allow configuring Sentry taskworker concurrency via env by madest92 in #4149

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