[lldb] Disable TestDAP_attachByPortNum

This test is flaky and creating a lot of noise in CI.
See llvm#137660

(cherry picked from commit b73169a)

Author: felipepiovezan

lldb/test/API/tools/lldb-dap/attach/TestDAP_attachByPortNum.py

@@ -19,6 +19,7 @@
 import socket
 
 
+@skipIf
 class TestDAP_attachByPortNum(lldbdap_testcase.DAPTestCaseBase):
     default_timeout = 20