[clang][DebugInfo] Don't emit VTable debug symbols for -gline-tables-only. (#151025)
The -gline-tables-only option emits minimal debug info for functions,
files and line numbers while omitting variables, parameters and most
type information. VTable debug symbols are emitted to facilitate a
debugger's ability to perform automatic type promotion on variables and
parameters. With variables and parameters being omitted, the VTable
symbols are unnecessary.