test(debugger): remove 3.9 exploration runs [backport 4.8] (#17779)

Backport #17777 to 4.8

Co-authored-by: emmettbutler <723615+emmettbutler@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: emmett.butler <emmett.butler@datadoghq.com>

Author: 3 people

.gitlab/debugging-exploration.yml

@@ -23,9 +23,6 @@
       artifacts: true
       parallel:
         matrix:
-          - ARCH_TAG: "amd64"
-            PYTHON_TAG: "cp39-cp39"
-            IMAGE_TAG: "v85383392-751efc0-manylinux2014_x86_64"
           - ARCH_TAG: "amd64"
             PYTHON_TAG: "cp310-cp310"
             IMAGE_TAG: "v85383392-751efc0-manylinux2014_x86_64"
@@ -78,7 +75,7 @@
     DD_DEBUGGER_EXPL_INCLUDE: "boto3"
   parallel:
     matrix:
-      - PYTHON_VERSION: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+      - PYTHON_VERSION: ["3.10", "3.11", "3.12", "3.13", "3.14"]
   script: |
     git clone --depth 1 --branch ${BOTO3_TAG} https://github.com/boto/boto3.git
     cd boto3
@@ -105,7 +102,7 @@
     DD_DEBUGGER_EXPL_COVERAGE_INSTRUMENTATION_RATE: "0.01"
   parallel:
     matrix:
-      - PYTHON_VERSION: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+      - PYTHON_VERSION: ["3.10", "3.11", "3.12", "3.13", "3.14"]
   script: |
     git clone --depth 1 --branch ${BOTO3_TAG} https://github.com/boto/boto3.git
     cd boto3