Tests: Run tests on both real Firefox ESRs

1. At the same time, there may be two supported versions of Firefox ESR. Run
   tests on both, installed locally.
2. Don't run tests on Firefox 115 on BrowserStack - it was added as there's
   an ESR version of Firefox 115, but ESR versions may be different, e.g. for
   some time ServiceWorker was disabled on ESR versions:
   https://bugzilla.mozilla.org/show_bug.cgi?id=1547023

Closes gh-5547

.github/workflows/browserstack.yml

@@ -31,7 +31,6 @@ jobs:
           - 'Edge_latest-1'
           - 'Firefox_latest'
           - 'Firefox_latest-1'
-          - 'Firefox_115'
           - '__iOS_17'
           - '__iOS_16'
           - '__iOS_15'

.github/workflows/node.js.yml

@@ -37,7 +37,10 @@ jobs:
           - NAME: "Chrome"
             NODE_VERSION: "20.x"
             NPM_SCRIPT: "test:esm"
-          - NAME: "Firefox ESR"
+          - NAME: "Firefox ESR (new)"
+            NODE_VERSION: "20.x"
+            NPM_SCRIPT: "test:firefox"
+          - NAME: "Firefox ESR (old)"
             NODE_VERSION: "20.x"
             NPM_SCRIPT: "test:firefox"
     steps:
@@ -57,10 +60,21 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-node-${{ matrix.NODE_VERSION }}-npm-lock-
 
-      - name: Install firefox ESR
+      - name: Set download URL for Firefox ESR (old)
+        run: |
+          echo "FIREFOX_SOURCE_URL=https://download.mozilla.org/?product=firefox-esr-latest-ssl&lang=en-US&os=linux64" >> "$GITHUB_ENV"
+        if: contains(matrix.NAME, 'Firefox ESR (old)')
+
+      - name: Set download URL for Firefox ESR (new)
+        run: |
+          echo "FIREFOX_SOURCE_URL=https://download.mozilla.org/?product=firefox-esr-next-latest-ssl&lang=en-US&os=linux64" >> "$GITHUB_ENV"
+        if: contains(matrix.NAME, 'Firefox ESR (new)')
+
+      - name: Install Firefox ESR
         run: |
-          export FIREFOX_SOURCE_URL='https://download.mozilla.org/?product=firefox-esr-latest-ssl&lang=en-US&os=linux64'
           wget --no-verbose $FIREFOX_SOURCE_URL -O - | tar -jx -C ${HOME}
+          echo "PATH=${HOME}/firefox:$PATH" >> "$GITHUB_ENV"
+          echo "FIREFOX_BIN=${HOME}/firefox/firefox" >> "$GITHUB_ENV"
         if: contains(matrix.NAME, 'Firefox ESR')
 
       - name: Install dependencies
@@ -71,10 +85,7 @@ jobs:
         if: contains(matrix.NPM_SCRIPT, 'lint')
 
       - name: Run tests
-        run: |
-          export PATH=${HOME}/firefox:$PATH
-          export FIREFOX_BIN=${HOME}/firefox/firefox
-          npm run ${{ matrix.NPM_SCRIPT }}
+        run: npm run ${{ matrix.NPM_SCRIPT }}
 
   safari:
     runs-on: macos-latest