Revert "[TEST] Disable dummy documents for QueryRescorerTests#testEquivalence"

This reverts commit 1bee019371b1776a8c443f1474a4a9358c96df45.
Revert "[TEST] Provide overloaded indexRandom to opt out of dummy documents"

This reverts commit ee43803486df879354fa0a79cd67455ebcc8dec2.
Revert "Add dummy docs injection to indexRandom"

This reverts commit beffc1893500cca102e9ed58d4e57030a32000f0.