chore(iast): removing redundant operations

[avara1986]

Removing redundant operations:

• call start_iast_context with span to skip a core.get_span() call
• remove redundant calls to asm_config.is_iast_request_enabled and asm_config._iast_enabled
• remove @WeakHash.wrap because it's a redundant call to asm_config.is_iast_request_enabled

This PR is part of #13347

APPSEC-57161

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:

ddtrace/appsec/_deduplications.py                                       @DataDog/asm-python
ddtrace/appsec/_iast/_iast_request_context_base.py                      @DataDog/asm-python
ddtrace/appsec/_iast/constants.py                                       @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/_base.py                               @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/code_injection.py                      @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/header_injection.py                    @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/insecure_cookie.py                     @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/sql_injection.py                       @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/weak_cipher.py                         @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/weak_hash.py                           @DataDog/asm-python
tests/appsec/iast/test_processor.py                                     @DataDog/asm-python
tests/appsec/iast/test_telemetry.py                                     @DataDog/asm-python

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

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

The average import time from base is: 235 ± 2 ms.

The import time difference between this PR and base is: -2.33 ± 0.1 ms.

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 2.079 ms (0.89%)

ddtrace.bootstrap.sitecustomize 1.364 ms (0.59%)

ddtrace.bootstrap.preload 1.364 ms (0.59%)

ddtrace.internal.remoteconfig.client 0.668 ms (0.29%)

ddtrace 0.715 ms (0.31%)

ddtrace._logger 0.036 ms (0.02%)

logging 0.036 ms (0.02%)

traceback 0.036 ms (0.02%)

contextlib 0.036 ms (0.02%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-05-14 20:17:17

Comparing candidate commit 5f43a90 in PR branch avara1986/APPSEC-57161_new_iast_sampling_3 with baseline commit 83dea4c in branch main.

Found 0 performance improvements and 4 performance regressions! Performance is the same for 431 metrics, 5 unstable metrics.

scenario:iast_aspects-ljust_aspect

• 🟥 execution_time [+1.308µs; +1.489µs] or [+10.139%; +11.542%]

scenario:iast_aspects-lower_aspect

• 🟥 execution_time [+246.159ns; +292.511ns] or [+11.093%; +13.182%]

scenario:iast_aspects-rstrip_aspect

• 🟥 execution_time [+1.272µs; +1.386µs] or [+9.928%; +10.824%]

scenario:telemetryaddmetric-1-distribution-metric-1-times

• 🟥 execution_time [+348.096ns; +437.955ns] or [+11.441%; +14.395%]