[TASK] Simplify EXT:solr tests stack

Prep. for CI-Deps in standalone directory and moving from require-dev on all EXT:solr* repos.

Author: dkd-kaehm

Build/Test/phpstan.neon

@@ -6,7 +6,7 @@ parameters:
   treatPhpDocTypesAsCertain: false
 
   bootstrapFiles:
-    - %rootDir%/../../apache-solr-for-typo3/solr/Build/Test/phpstan-constants.php
+    - %env.COMPOSER_VENDOR_DIR%/apache-solr-for-typo3/solr/Build/Test/phpstan-constants.php
 
   paths:
     - %currentWorkingDirectory%/Classes

composer.json

@@ -137,7 +137,7 @@
     "tests:unit": [ "phpunit --colors -c Build/Test/UnitTests.xml" ],
     "tests:integration": [ "phpunit --colors -c Build/Test/IntegrationTests.xml" ],
     "tests:phpstan": [
-      "phpstan analyze -c Build/Test/phpstan.neon"
+      "COMPOSER_VENDOR_DIR=$($COMPOSER_BINARY config vendor-dir) phpstan analyze -c Build/Test/phpstan.neon"
     ],
     "t3:standards:fix": [
       "php-cs-fixer fix"