Migrate deprecated AllBranchesLogCmd to AllBranchesLogCmds

[ChrisMcD1]

• PR Description

Fixes #3961

Their issue where the default allBranchesLogCmd default remains present is because we just do a lo.Uniq(lo.WithoutEmpty()) on the combined list of allBranchesLogCmd and allBranchesLogCmds.

At the point of this code, it is not possible to tell whether the value present in allBranchesLogCmd is user-provided or not. We have already merged the config with the default config, so the user not setting anything, and the user explicitly setting "Yes, I want the default", are indistinguishable.

Based on that bug report, I'm assuming that users that have not set anything for allBranchesLogCmd, but have set something for allBranchesLogCmds, just want the list they have specified in the plural version. Some users have likely figured out they can explicitly set allBranchesLogCmd: "" to get this behavior, but most would not.

To achieve this desired behavior, I figure it is easiest to just migrate all user config to allBranchesLogCmds. If they have explicitly set a non-empty value in allBranchesLogCmd, it will be pulled over. If they set an empty string, it will be excluded.

• Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go generate ./...)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• If a new UserConfig entry was added, make sure it can be hot-reloaded (see here)
• Docs have been updated if necessary
• You've read through your own file changes for silly mistakes etc