Remove Static Variables

[LucasYuki]

Description

OpenROAD shouldn't use any static variables under the hood that aren’t somehow guarded by a lock.

Static variables per module:

• [ ] cts - 1 static variable
• [ ] drt - 17 static variables
• [ ] gui - 12 static variables
• [ ] odb - 108 static variables
• [ ] rcx - 8 static variables
• [ ] rmp - 1 static variable
• [ ] sta - 166 static variables
• [ ] stt - 7 static variables

Suggested Solution

@eder-matheus suggested working on one module at a time, making a PR for each one.

Additional Context

No response

[maliberty]

sta is special so let's address it last and discuss first.

[maliberty]

odb::db_tbl
odb::db_unique_id

fixed in #6192

[maliberty]

odb::conn fixed in #6190

[maliberty]

odb::ttttsv fixed in #6191

[maliberty]

log_filename
metrics_filename

fixed in #6194

[maliberty]

cts::HTreeBuilder::plotSolution()::cnt fixed in #6195

[maliberty]

@LucasYuki no need to do gui (excluded from the current plan).

[maliberty]

@QuantamHD agreed to handle the one in rmp (discussed in #5989)

[maliberty]

sta to be managed separately