Revert "ci: enable running libc-test on x86_64-linux-release"

This reverts commit fcfdf99.

This added too much load to the x86_64-linux machines, resulting in timeouts
pretty much across the board.

Author: alexrp

ci/x86_64-linux-release.sh

@@ -56,7 +56,6 @@ stage3-release/bin/zig build \
 stage3-release/bin/zig build test docs \
   --maxrss 21000000000 \
   -Dlldb=$HOME/deps/lldb-zig/Release-e0a42bb34/bin/lldb \
-  -Dlibc-test-path=$HOME/deps/libc-test-f2bac77 \
   -fqemu \
   -fwasmtime \
   -Dstatic-llvm \