Reduce TTIGW protocol disconnects based on missed pongs

[johanstokking]

Summary

This reduces the number of TTIGW protocol disconnections because of not receiving pong answers to pings in time.

The ping timeout and interval are now aligned with the Gateway Controller. The Gateway Controller marks far less gateway connections as disconnected for the same gateway during the same time frame, suggesting that The Things Stack unnecessarily marks gateway connections gone.

Changes

• Increase ping interval from 30 seconds to 1 minute
• Increase ping timeout from 10 seconds to 30 seconds

Testing

We'll observe this in operational metrics.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Testing: The steps/process to test this feature are clearly explained including testing for regressions.
• Infrastructure: If infrastructural changes (e.g., new RPC, configuration) are needed, a separate issue is created in the infrastructural repositories.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[happyRip]

LGTM