ci(gitlab): use templates in dynamic configuration

[P403n1x87]

We make the dynamic configuration generation script leaner by taking out literal tempate strings into template files.

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
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• [ ] 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 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

[github-actions[bot]]

CODEOWNERS have been resolved as:

.gitlab/templates/build-base-venvs.yml                                  @DataDog/python-guild @DataDog/apm-core-python
.gitlab/templates/cached-testrunner.yml                                 @DataDog/python-guild @DataDog/apm-core-python
scripts/gen_gitlab_config.py                                            @DataDog/apm-core-python

[github-actions[bot]]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 281 ± 6 ms.

The average import time from base is: 278 ± 4 ms.

The import time difference between this PR and base is: 2.9 ± 0.2 ms.

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 1.219 ms (0.43%)

ddtrace 0.664 ms (0.24%)

ddtrace.internal._unpatched 0.026 ms (0.01%)

json 0.026 ms (0.01%)

json.decoder 0.026 ms (0.01%)

re 0.026 ms (0.01%)

enum 0.026 ms (0.01%)

types 0.026 ms (0.01%)

ddtrace.bootstrap.sitecustomize 0.555 ms (0.20%)

ddtrace.bootstrap.preload 0.555 ms (0.20%)

ddtrace.internal.remoteconfig.client 0.555 ms (0.20%)

[pr-commenter[bot]]

Benchmarks

Benchmark execution time: 2025-06-27 15:06:14

Comparing candidate commit b20ce6630a9e7aa8550d5efab95552f5f837f6f2 in PR branch ci/use-template-in-dynamic-config with baseline commit 5fdd9c23c8f9886d201335b8b2ac141fc95bc517 in branch main.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 522 metrics, 3 unstable metrics.

scenario:iastaspects-replace_aspect

• 🟥 execution_time [+706.087ns; +768.571ns] or [+14.852%; +16.166%]