Remove obsolete and time consuming Java 7 issue #51 regression test #756

Job	Run time
Build it / fail-fast-build	41s
Build it / ubuntu-latest jdk-21-zulu	44s
Build it / macos-latest jdk-8-zulu	56s
Build it / macos-latest jdk-21-zulu	50s
Build it / windows-latest jdk-21-zulu	1m 24s
Build it / ubuntu-latest jdk-25-zulu	52s
Build it / windows-latest jdk-25-zulu	1m 21s
Build it / ubuntu-latest jdk-8-zulu	37s
Build it / windows-latest jdk-8-zulu	1m 16s
Build it / macos-latest jdk-25-zulu	43s
Deploy / Deploy	0s
	9m 24s

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