NIFI-8772 - address Maven build warnings

[greyp9]

Thank you for submitting a contribution to Apache NiFi.

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Description of PR

Fix Maven POM parent/child inconsistencies. Address Maven build warnings.

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[greyp9]

[WARNING] Some problems were encountered while building the effective model for org.apache.nifi:nifi-graph-processors🫙1.14.0-SNAPSHOT
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.nifi:nifi-record-serialization-service-api:jar -> version (?) vs 1.14.0-SNAPSHOT @ line 98, column 21

[greyp9]

[WARNING] Some problems were encountered while building the effective model for org.apache.nifi.registry:nifi-registry-web-api:war:1.14.0-SNAPSHOT
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.spockframework:spock-core:jar -> duplicate declaration of version (?) @ line 480, column 21

[greyp9]

https://github.com/apache/nifi/blob/main/nifi-external/nifi-example-bundle/pom.xml#L30

[greyp9]

https://github.com/apache/nifi/blob/main/nifi-nar-bundles/nifi-standard-services/nifi-ssl-context-bundle/nifi-ssl-context-nar/pom.xml#L22

[exceptionfactory]

Thanks for correcting these issues @greyp9, looks good! +1 Merging.