RFR(T): 8241975: Run jdk/jfr/event/metadata/TestLookForUntestedEvents.java in tier3

[mikhailo.seledtsov at oracle.com]

Please review this trivial change that adds 
TestLookForUntestedEvents.java to jdk-tier3.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8241975

     Change:
         diff --git a/test/jdk/TEST.groups b/test/jdk/TEST.groups
         --- a/test/jdk/TEST.groups
         +++ b/test/jdk/TEST.groups
         @@ -76,7 +76,8 @@
                :jdk_beans \
                :jdk_imageio \
                :jdk_sound \
           -    :jdk_client_sanity
           +    :jdk_client_sanity \
           +    :jdk_jfr_tier3

###############################################################################
           #
           @@ -279,6 +280,9 @@
            jdk_jfr = \
                jdk/jfr

            +jdk_jfr_tier3 = \
            + jdk/jfr/event/metadata/TestLookForUntestedEvents.java
            +


     Testing:
         1. Locally:
            jtreg open/test/jdk/:jdk_jfr_tier3
            PASS
         2. Making sure the test is part of the jdk tier3:
            jtreg -l open/test/jdk/:tier3 | grep TestLookForUntestedEvents
            Found
         3. Test System: running jdk_tier3: in progress


Thank you,
Misha