Eclipse: Move LanguageServer Logging Preferences to Eclipse-Tree Element

[bohni]

Eclipse Preference UI has a "Logs" entry for Language Servers. So the "Spring Language Servers" entry is no longer necessary.

[martinlippert]

The log settings in the Language Servers - Logs section do log information about the communication between the IDE and the language server (basically the messages that are going forth and back).

The specific log setting for the Spring Boot language server will ask the language server itself to write detailed process log output to the console and/or a file, so this is different.

It would make some sense to unify this, but we would at least need to option to configure different log files for the different outputs (the messaging as well as the detailed log from the server process).