Rename flag depth in TxPool

[AurelienFT]

Linked Issues/PRs

Resolves #2313

Description

This PR renames a flag that hasn't been updated with new tx pool to avoid breaking change but that flag name isn't approriate anymore.
@xgreenx whenever you are confortable with pushing this breaking change ping here and I will update the CHANGELOG and change the PR to ready for review.

Checklist

• Breaking changes are clearly marked as such in the PR description and changelog
• New behavior is reflected in tests
• The specification matches the implemented behavior (link update PR if changes are needed)

Before requesting review

• I have reviewed the code myself
• I have created follow-up issues caused by this PR and linked them here

After merging, notify other teams

[Add or remove entries as needed]

• Rust SDK
• Sway compiler
• Platform documentation (for out-of-organization contributors, the person merging the PR will do this)