Lazy configuration processing, printing all errors at once

This PR changes the way how we handle configuration errors during startup. The original logic stopped on first encountered error, forcing user to fix it and try again, which could repeat several times and leads to tiresome process. The new logic discovers and reports all problems at once, making it easy to fix in one go.

Removed duplicated configuration processing during the datanode startup, which I assume, was a copy-paste error.

Description

See https://github.com/Graylog2/JadConfig/pull/127

Motivation and Context

Fixes https://github.com/Graylog2/graylog2-server/issues/19207

How Has This Been Tested?

Manually

Screenshots (if appropriate):

Before, stopping at the first error:

2024-07-02 09:19:25,504 ERROR: org.graylog.datanode.bootstrap.CmdLineTool - Invalid configuration
com.github.joschi.jadconfig.ParameterException: Required parameter "opensearch_data_location" not found.
    at com.github.joschi.jadconfig.JadConfig.processClassField(JadConfig.java:173) ~[jadconfig-0.15.0.jar:?]
    at com.github.joschi.jadconfig.JadConfig.processClassFields(JadConfig.java:143) ~[jadconfig-0.15.0.jar:?]
    at com.github.joschi.jadconfig.JadConfig.process(JadConfig.java:103) ~[jadconfig-0.15.0.jar:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.processConfiguration(CmdLineTool.java:422) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.parseAndGetConfiguration(CmdLineTool.java:310) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.doRun(CmdLineTool.java:266) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.run(CmdLineTool.java:246) [classes/:?]
    at org.graylog.datanode.bootstrap.Main.main(Main.java:57) [classes/:?]

After, collecting all errors and then failing:

2024-07-02 09:21:06,927 ERROR: org.graylog.datanode.bootstrap.CmdLineTool - Invalid configuration
com.github.joschi.jadconfig.LazyValidationException: Following errors ocurred during configuration processing:
Required parameter "opensearch_data_location" not found.
Required parameter "opensearch_config_location" not found.
Required parameter "opensearch_logs_location" not found.
    at com.github.joschi.jadconfig.JadConfig.processFailingLazily(JadConfig.java:118) ~[jadconfig-0.15.0.jar:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.processConfiguration(CmdLineTool.java:422) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.parseAndGetConfiguration(CmdLineTool.java:310) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.doRun(CmdLineTool.java:266) [classes/:?]
    at org.graylog.datanode.bootstrap.CmdLineTool.run(CmdLineTool.java:246) [classes/:?]
    at org.graylog.datanode.bootstrap.Main.main(Main.java:57) [classes/:?]

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Refactoring (non-breaking change)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[x] I have read the CONTRIBUTING document.
[ ] I have added tests to cover my changes.

Graylog2 / graylog2-server