Remove some tests which were marked flaky.

Change-Id: Ibd0d153b994dbeaada4d55242ed529f20465362c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/434780
Reviewed-by: Alexander Aprelev <[email protected]>
Commit-Queue: Siva Annamalai <[email protected]>

Author: a-siva

tests/standalone/standalone.status

@@ -94,8 +94,6 @@ dwarf_stack_trace_test: SkipByDesign # Due to instruction canonicalization we ca
 io/http_basic_test: Slow, Pass # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
 
 [ $system == macos && ($runtime == dart_precompiled || $runtime == vm) ]
-io/raw_secure_server_socket_test: Crash
-io/raw_server_socket_cancel_test: Skip # Issue 28182 # This test sometimes hangs on Mac.
 io/socket_many_connections_test: Skip # This test fails with "Too many open files" on the Mac OS buildbot. This is expected as MacOS by default runs with a very low number of allowed open files ('ulimit -n' says something like 256).
 
 [ $compiler == dart2js || $compiler == dart2wasm || $compiler == ddc ]