Backport #33239 to 1.54.

Co-authored-by: Craig Tiller <ctiller@google.com>

…#33303)

We configured TestGrid to file bug separately for each failed
sub-target, if we still fail the main target, TestGrid will fail
duplicate bugs.




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…(v1.54.x backport) (#33525)

Backport of #33520 to v1.54.x.
---
Follow up change of #33222.

We don't want file multiple bugs if any of the sub-tests of the
`url_map` test fails.

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…ptor exhaustion (#33670)

Backport of #33656

PanCakes to the rescue!

We noticed that our 'sanity' test was going to fail, but we think we can
fix that automatically, so we put together this PR to do just that!

If you'd like to opt-out of these PR's, add yourself to NO_AUTOFIX_USERS
in .github/workflows/pr-auto-fix.yaml

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

Generated by release script

…v1.54.x backport) (#33725)

Backport of #33699 to v1.54.x.
---
Similar to grpc/grpc-java#8982.
All other languages already to this.

Needed for easier deployment of #33685.

ref b/274944592

…rt) (#33809)

Backport of #33796 to v1.54.x.
---
#33699 incorrectly changed the legacy
builds to not just use the test driver from the master, but also to
build from it. This PR fixes the issue, and also updates the python job
to work use the driver from master.

*Beep boop. This is an automatically generated backport of #33738.*

This should resolve breakage on master caused by the jump to Cython
3.0.0 this morning.

Update Phusion base image to address security issues. Original PR:
#33847