gh actions: separate explicit-fastmachines CI from unrestricted one

.github/workflows/stainless-CI.yml

@@ -8,7 +8,6 @@ on:
 jobs:
   tests:
     runs-on:
-      group: fast-machines
       labels: [self-hosted, linux]
     env:
       JAVA_OPTS_TMP_DIR: ./tmp_java

.github/workflows/stainless-explicit-fastmachines.yml

@@ -0,0 +1,50 @@
+name: Stainless Explicit fast-machines
+on:
+  workflow_dispatch:
+  pull_request:
+jobs:
+  tests:
+    runs-on:
+      group: fast-machines
+      labels: [self-hosted, linux]
+    env:
+      JAVA_OPTS_TMP_DIR: ./tmp_java
+      # define Java options for both official sbt and sbt-extras
+      JAVA_OPTS: -Dsbt.io.implicit.relative.glob.conversion=allow -Xss512M -Xms1024M -Xmx12G -XX:MaxMetaspaceSize=2G -XX:+UseCodeCacheFlushing -XX:ReservedCodeCacheSize=768M -Djava.io.tmpdir=$JAVA_OPTS_TMP_DIR 
+      JVM_OPTS:  -Dsbt.io.implicit.relative.glob.conversion=allow -Xss512M -Xms1024M -Xmx12G -XX:MaxMetaspaceSize=2G -XX:+UseCodeCacheFlushing -XX:ReservedCodeCacheSize=768M -Djava.io.tmpdir=$JAVA_OPTS_TMP_DIR
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        submodules: recursive
+    - name: Setup JDK
+      uses: actions/setup-java@v4
+      with:
+        distribution: temurin
+        java-version: 17
+    - name: Install and unpack sbt
+      run: |
+        wget https://github.com/sbt/sbt/releases/download/v1.10.1/sbt-1.10.1.tgz
+        tar xfz sbt-1.10.1.tgz
+        echo "PATH=./sbt/bin/:$PATH" >> "$GITHUB_ENV"
+    - name: Install solvers
+      run: ./stainless-ci.sh --install-solvers $GITHUB_WORKSPACE/.local/bin
+    - name: Add solvers to PATH
+      run: echo "$GITHUB_WORKSPACE/.local/bin" >> $GITHUB_PATH
+    - name: Test solvers availability
+      run: cvc5 --version && z3 --version && cvc4 --version
+    - name: Build and Package
+      run: ./stainless-ci.sh --build-only
+    - name: Run Tests and Integration Tests
+      run: ./stainless-ci.sh --skip-build --skip-bolts --skip-sbt-plugin 
+    - name: Sbt Plugin Tests
+      run: ./stainless-ci.sh --skip-build --skip-tests --skip-bolts
+    - name: Clean up
+      run: rm -rf $JAVA_OPTS_TMP_DIR
+  fail_if_pull_request_is_draft:
+    if: github.event.pull_request.draft == true
+    runs-on: [self-hosted, linux]
+    steps:
+    - name: Fails in order to indicate that pull request needs to be marked as ready to review and tests workflows need to pass.
+      run: exit 1
+