chore: extend flaky until timestamp for grpc (#11399)

As part of #11274, the
previous `until` timestamp for grpc was Oct 2024 which has already
passed. Unless anyone knows about ipv6 support, this PR extends the
timestamp until Jan 2025 to buy some more time.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: wantsui

tests/contrib/grpc/test_grpc.py

@@ -669,7 +669,7 @@ def service(self, handler_call_details):
 
 
 @snapshot(ignores=["meta.network.destination.port"], wait_for_num_traces=2)
-@flaky(until=1729294610, reason="GitLab CI does not support ipv6 at this time")
+@flaky(until=1738272799, reason="GitLab CI does not support ipv6 at this time")
 def test_method_service(patch_grpc):
     def handler(request, context):
         return b""