Do not propagate option `--get-random` to Vogar in `run-libcore-tests.sh`.

This bit was missing from commit
d6e2c388d0d91c0e7cce66147cc188caed3208b6.

Test: art/tools/run-libcore-tests.sh --mode=device --no-getrandom
Test: Rely on the ART Buildbot.
Bug: 141230711
Change-Id: I25742c477594f9127c79054850787742b9086f43
diff --git a/tools/run-libcore-tests.sh b/tools/run-libcore-tests.sh
index 5f49bbe..4c39445 100755
--- a/tools/run-libcore-tests.sh
+++ b/tools/run-libcore-tests.sh
@@ -168,6 +168,8 @@
     gcstress=true
     shift
   elif [[ "$1" == "--no-getrandom" ]]; then
+    # Remove the option from Vogar arguments.
+    vogar_args=${vogar_args/$1}
     getrandom=false
     shift
   elif [[ "$1" == "" ]]; then