fix(newrelic_nrql_alert_condition): add default 'violation_time_limit_seconds'

[pranav-new-relic]

Description

• Addresses NR-97003
• Adds a default 'violation_time_limit_seconds' of 259200 seconds to the newrelic_nrql_alert_condition resource
• Fixes issues identified with re-applying terraform plan after the first terraform apply is executed, because a null violation_time_limit_seconds is defaulted to 259200 seconds (3 days), which is expected behaviour, as specified here.

Fixes #2245

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My commit message follows conventional commits
• My code is formatted to Go standards
• I have performed a self-review of my own code
• New and existing unit tests pass locally with my changes. Go here for instructions on running tests locally.