Disable "fail on warning" in GitHub Actions and Jenkins builds

The GitHub Actions and Jenkins build specifications currently contain
the option `-Dmaven.compiler.failOnWarning=true`. Since warnings were
defined to be ignored in the parent POM, this did not have any effect.
The configuration to ignore warnings has been removed from the parent
POM, so that the builds now fail as the code actually contains warnings.

This change removes the "fail on warning" option. Warnings are still
considered via Jenkins quality gates.

.github/workflows/maven.yml

@@ -68,7 +68,6 @@ jobs:
         -Dnative=${{ matrix.config.native }}
         -Dcompare-version-with-baselines.skip=true
         -Dtycho.baseline.replace=none
-        -Dmaven.compiler.failOnWarning=true
         --fail-at-end
         -DskipNativeTests=false
         -DfailIfNoTests=false
@@ -81,7 +80,6 @@ jobs:
         mvn --batch-mode -V -U
         -DforkCount=1
         -Dcompare-version-with-baselines.skip=true
-        -Dmaven.compiler.failOnWarning=true
         --fail-at-end
         -DskipNativeTests=true
         -DfailIfNoTests=true

Jenkinsfile

@@ -300,7 +300,7 @@ pipeline {
 						sh '''
 							mvn clean verify \
 								--batch-mode --threads 1C -DforkCount=0 \
-								-Dcompare-version-with-baselines.skip=false -Dmaven.compiler.failOnWarning=true \
+								-Dcompare-version-with-baselines.skip=false \
 								-Dorg.eclipse.swt.tests.junit.disable.test_isLocal=true \
 								-Dmaven.test.failure.ignore=true -Dmaven.test.error.ignore=true
 						'''