avoid global isHistoryEnabled() checks in favor of per repository check

[vladak]

This change allows for real per project history override.

Tested with indexer running with:

-P
-S
-R
/var/opengrok/etc/readonly_configuration-per_project_history.xml
-s
/var/opengrok/src.perproj
-d
/var/opengrok/data.perproj
-W
/var/opengrok/etc/configuration.xml

where the contents of /var/opengrok/etc/readonly_configuration-per_project_history.xml looked like this:

<?xml version="1.0" encoding="UTF-8"?>
<java version="11.0.4" class="java.beans.XMLDecoder">
 <object class="org.opengrok.indexer.configuration.Configuration" id="Configuration0">

  <void property="historyEnabled">
    <boolean>true</boolean>
  </void>

  <void property="projectsEnabled">
   <boolean>true</boolean>
  </void>

   <void property="projects">
     <void method="put">
      <string>foo</string>
      <object class="org.opengrok.indexer.configuration.Project">
       <void property="handleRenamedFiles">
        <boolean>false</boolean>
       </void>
       <void property="historyEnabled">
        <boolean>false</boolean>
       </void>
       <void property="name">
        <string>foo</string>
       </void>
       <void property="path">
        <string>/foo</string>
       </void>
       <void property="mergeCommitsEnabled">
        <boolean>false</boolean>
       </void>
      </object>
     </void>
   </void>

 </object>
</java>

The source root had two projects, each with single Git repository, named foo and bar. I ran two tests, one with global history on and per project/repository off and vice versa. Checked the list/minisearch JSPs in debugger for each test.

Also ran indexer with and without -H to make sure the history is disabled by default as before the change and also that the history cache is created if history is on (to test the AnalyzerGuru changes).

Also tested in project-less mode.