[Bug]: sql诊断时如果涉及的表跨db，取不到schema信息

[Zxf-xufeng]

Describe the bug

sql诊断时如果涉及的表跨db，取不到schema信息，会是变量信息

Environment

4.x

Fast reproduce steps

执行sql，sql的表里面分布在不同的database中，再用命令取sql诊断信息。obdiag gather plan_monitor --trace_id YBxxxxx --env "{db_connect='-hxx -Pxx -uxx -pxx -Dxx'}"

Expected behavior

No response

Actual behavior

No response

Additional context

No response