Use fail-fast: false throughout consistently

In the pullrequest.yml we use "fail-fast: false", but on main.yml we use
 "continue-on-error: true". The former is intended for matrices (which
 we use throughout) and the latter for proceeding through steps (while
 we use it for the entire job). To clarify the GHA ymls, use fail-fast:
 false throughout instead.

#enhancement/fail-fast-setting-consolidation

.github/workflows/main.yml

@@ -11,9 +11,8 @@ jobs:
   build:
     name: Test and Build on JDK ${{ matrix.java-version }}
     runs-on: ubuntu-latest
-    continue-on-error: true # do not fail the whole job if one of the steps fails
-
     strategy:
+      fail-fast: false
       matrix:
         include:
           - java-version: 8

.github/workflows/pullrequest.yml

@@ -8,6 +8,7 @@ jobs:
     name: Test and Build on JDK ${{ matrix.java-version }}
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         include:
           - java-version: 8
@@ -16,7 +17,6 @@ jobs:
             sonar-enabled: false
           - java-version: 17
             sonar-enabled: true
-      fail-fast: false # run all to the end
 
     steps:
       - name: Checkout code