Remove maximum time cap on entered timetable string.

[philip-cline]

Checklist

• [x] Appropriate branch selected (all PRs must first be merged to dev before they can be merged to master)
• [x] Any modified or new methods or classes have helpful JSDoc and code is thoroughly commented
• [x] The description lists all applicable issues this PR seeks to resolve
• [x] The description lists any configuration setting(s) that differ from the default settings
• [x] All tests and CI builds passing

Description

There is currently a maximum time string of "34:00:00" that can be entered into the timetable editor. Some users, such as very long distance rail carriers, may require times above this. This PR removes any maximum on the times that may be entered into the editor.