#1956: Fix MAVEN_ARGS bug

[laert-ll]

This PR fixes #1956

Implemented changes:

• Extend mergeWithDefault method in AbstractEnvironmentVariables.java to account for the desired functionality.
• Add new test case for this change.

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Testing instructions

icd -p IDEasy
echo 'export MAVEN_ARGS="-Xmx8000m -s invalid/settings.xml -Dsettings.security=something_wrong"' >> conf/ide.properties
ide
echo $MAVEN_ARGS

Expected behavior:

-Xmx8000m -s D:\projects\IDEasy\conf\mvn\settings.xml -Dsettings.security=D:\projects\IDEasy\conf\mvn\settings-security.xml

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Checklist for this PR

Make sure everything is checked before merging this PR. For further info please also see
our DoD.

• When running mvn clean test locally all tests pass and build is successful
• PR title is of the form #«issue-id»: «brief summary» (e.g. #921: fixed setup.bat). If no issue ID exists, title only.
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  with internal
• You have formulated clear instructions on how to test your contribution under "Testing instructions"

[coveralls]

Coverage Report for CI Build 27125044684

Coverage increased (+0.04%) to 71.092%

Details

• Coverage increased (+0.04%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 1 coverage regression across 1 file.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

1 previously-covered line in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
com/devonfw/tools/ide/tool/ide/IdeToolCommandlet.java	1	78.33%

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Coverage Stats

Relevant Lines:	15833
Covered Lines:	11742
Line Coverage:	74.16%
Relevant Branches:	7074
Covered Branches:	4543
Branch Coverage:	64.22%
Branches in Coverage %:	Yes
Coverage Strength:	3.14 hits per line

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💛 - Coveralls