Restrict cache trigger event to reduce cache usage

.github/workflows/build-gem.yml

@@ -10,7 +10,10 @@ on:
         default: true
   push:
     branches:
-      - "**"
+    - master
+  pull_request:
+    branches:
+    - master
 
 env:
   GEM_HOST: 'https://rubygems.pkg.github.com/DataDog'

.github/workflows/check.yml

@@ -1,6 +1,11 @@
 name: Static Analysis
 on:
   push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}

.github/workflows/generate-supported-versions.yml

@@ -2,7 +2,6 @@ name: "Generate Supported Versions"
 
 on:
   workflow_dispatch:
-
 
 concurrency:
   group: ${{ github.workflow }}
@@ -20,7 +19,6 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@8388f20e6a9c43cd241131b678469a9f89579f37 # v1.216.0
         with:
-          bundler-cache: true # runs bundle install
           ruby-version: "3.3"
 
       - name: Update latest
@@ -45,6 +43,6 @@ jobs:
             as defined from the `gemfile.lock` gem declarations.
 
             Workflow run: [Generate Supported Versions](https://github.com/DataDog/dd-trace-rb/actions/workflows/generate-supported-versions.yml)
-            
+
             This should be tied to tracer releases, or triggered manually.
 

.github/workflows/nix.yml

@@ -3,7 +3,10 @@ name: Test Nix
 on:
   push:
     branches:
-      - "**"
+    - master
+  pull_request:
+    branches:
+    - master
 
 jobs:
   test:

.github/workflows/test-macos.yaml

@@ -2,10 +2,10 @@ name: Test macOS
 on:
   push:
     branches:
-      - "**"
+    - master
   pull_request:
-    # The branches below must be a subset of the branches above
-    branches: [ master ]
+    branches:
+    - master
 jobs:
   test-macos:
     strategy:

.github/workflows/test-memory-leaks.yaml

@@ -1,5 +1,11 @@
 name: Test for memory leaks
-on: [push]
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
 jobs:
   test-memcheck:
     runs-on: ubuntu-24.04

.github/workflows/test-yjit.yaml

@@ -1,5 +1,11 @@
 name: Test YJIT
-on: [push]
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
 jobs:
   test-yjit:
     strategy: