fix(symdb): switch _shallow to shallow in install [backport 3.8]

[github-actions]

Backport 58bd69c from #13522 to 3.8.

This fixes a bug introduced by #12957 where the shallow mode for SymDB was introduced.

Checklist

• 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]

CODEOWNERS have been resolved as:

releasenotes/notes/fix-symdb-uploads-cfff7f4d568ff882.yaml              @DataDog/apm-python
ddtrace/internal/symbol_db/symbols.py                                   @DataDog/debugger-python
tests/internal/symbol_db/test_symbols.py                                @DataDog/debugger-python

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 230 ± 2 ms.

The average import time from base is: 232 ± 2 ms.

The import time difference between this PR and base is: -2.0 ± 0.1 ms.

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 1.946 ms (0.85%)

ddtrace.bootstrap.sitecustomize 1.274 ms (0.55%)

ddtrace.bootstrap.preload 1.274 ms (0.55%)

ddtrace.internal.remoteconfig.client 0.644 ms (0.28%)

ddtrace 0.672 ms (0.29%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-05-29 18:44:21

Comparing candidate commit 0140c6e in PR branch backport-13522-to-3.8 with baseline commit 5a941c1 in branch 3.8.

Found 0 performance improvements and 3 performance regressions! Performance is the same for 478 metrics, 7 unstable metrics.

scenario:iast_aspects-replace_aspect

• 🟥 execution_time [+657.810ns; +714.368ns] or [+14.245%; +15.470%]

scenario:iast_aspects-upper_aspect

• 🟥 execution_time [+223.089ns; +259.766ns] or [+9.735%; +11.336%]

scenario:iastdjangostartup-iast

• 🟥 execution_time [+155.117ms; +327.236ms] or [+7.276%; +15.349%]