SOLR-15839: Don't mock oal.search.Sort class (why the hell was this needed?)

[uschindler]

See https://issues.apache.org/jira/browse/SOLR-15839

[uschindler]

This is a fishy, stinky, and SNEAKY thing to mock!

[uschindler]

Sneaky test passes:

gradlew :solr:core:test --tests QueryComponentPartialResultsTest
To honour the JVM settings for this build a single-use Daemon process will be forked. See https://docs.gradle.org/7.2/userguide/gradle_daemon.html#sec:disabling_the_daemon.
Daemon will be stopped at the end of the build

> Task :randomizationInfo
Running tests with randomization seed: tests.seed=AE79BECFA5AFD6B4

> Task :solr:core:test
:solr:core:test (SUCCESS): 4 test(s)
The slowest suites (exceeding 1s) during this run:
   2.95s QueryComponentPartialResultsTest (:solr:core)