FindCompactionTmpFiles could fail more gracefully

[dlmarion]

Running FindCompactionTmpFiles with no arguments yields a stack trace instead of a usage statement or help.

~/Software/accumulo-4.0.0-SNAPSHOT/bin$ ./accumulo org.apache.accumulo.server.util.FindCompactionTmpFiles
2026-01-29T21:36:23,589 [util.FindCompactionTmpFiles] INFO : Looking for compaction tmp files over tables: null, deleting: false
Thread 'org.apache.accumulo.server.util.FindCompactionTmpFiles' died.
java.lang.NullPointerException: Cannot invoke "String.split(String)" because "opts.tables" is null
	at org.apache.accumulo.server.util.FindCompactionTmpFiles.main(FindCompactionTmpFiles.java:196)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at org.apache.accumulo.start.Main.lambda$execMainClass$1(Main.java:118)
	at java.base/java.lang.Thread.run(Thread.java:840)

[dlmarion]

This may be OBE with #4465 . If so, remove the main method from the utility if it still exists.