Adjust EnvironmentController for Path Pattern Parser

[hpoettker]

Fixes #2020 and #2021.

Config server URLs with paths like /{label}/{application}-{profile}.properties currently do not work as expected when Spring Web MVC uses PathPatternParser instead of AntPathMatcher. But with Spring Boot 2.6. the default matching strategy in the auto-configuration for Web MVC has been flipped to PathPatternParser.

This PR adjusts a regex in EnvironmentController such that both matching strategies work as expected. Furthermore, the Mock MVC tests for the controller are now executed with both strategies. As this is simpler with JUnit 5 than with Junit 4, the two test classes have been migrated.

[codecov]

Codecov Report

Merging #2031 (1913b2a) into 3.1.x (17ef04a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              3.1.x    #2031   +/-   ##
=========================================
  Coverage     77.22%   77.22%           
  Complexity     1442     1442           
=========================================
  Files           183      183           
  Lines          5362     5362           
  Branches        699      699           
=========================================
  Hits           4141     4141           
  Misses          950      950           
  Partials        271      271           

Impacted Files	Coverage Δ
...nfig/server/environment/EnvironmentController.java	91.95% <ø> (ø)

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