Support ES 7.8.0

[weicongs-amazon]

Issue #, if available:

Description of changes:

• Bump ODFE version to 1.9.0
• Update ES version to 7.8.0
• Use new Maven endpoint URL for ODFE (New Maven endpoint URL for ODFE #61)
• Fix the issues caused by breaking changes:
  • elastic/elasticsearch@b11960e
    * elastic/elasticsearch@5fcda57#diff-ddae67dbe9c67bff10339df6fa8d7301
• disable licenseHeaders and validateNebulaPom tasks to fix the issued caused by latest changes of es build tool
• update the IT gradle task for SPI which causes the maven pom file broken due to the latest changes of es build tool

Testing:

• ./gradle build
• ../gradlew publishShadowPublicationToSonatype-stagingRepository -Dcompiler.java=14 -Dbuild.snapshot=false -Djavax.net.ssl.trustStore=$JAVA_HOME/lib/security/cacerts
  • just verified that the pom file and related jars can be generated well

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ftianli-amzn]

I think removing the usage of 'elasticsearch.build' Gradle plugin is a big improvement, and it will effectively avoid more unexpected failure in the future.