Fix method tracing tests on RI

They were failing due to workarounds requiring us to disable tracing
for RI in some situations. We were checking that we only enabled the
tracing code once and not clearing it causing the test to incorrectly
fail with an error.

Test: ./test/run-test --host --jvm 990-field-trace
Test: ./test/run-test --host --jvm 991

Change-Id: I3820260a1954babc11497729d7c652dcd02bee80