ci: remove failOnError=false now that OWASP analyzer crash is fixed

The buildSrc classloader fix (f337ba6) made the analyzer run to
completion, so the tolerance flag added in 95c8f79 is no longer
needed. Reverting to the default (true) so a future analyzer
regression fails loudly instead of silently passing with an
incomplete report.

Author: symphony-enrico

build.gradle

@@ -61,5 +61,4 @@ repositories {
 dependencyCheck {
     failBuildOnCVSS=5
     suppressionFile="./allow-list.xml"
-    failOnError=false
 }