removeIf.md for ArrayList in Java

[hakdo99]

Description

Added file removeIf.md to explain the .removeIf() method as a new term entry for ArrayList in Java. The markdown file is placed under the file path content/java/concepts/array-list/terms/removeIf/removeIf.md

Issue Solved

Closes #4343

Type of Change

• Adding a new entry

Checklist

• [x ] All writings are my own.
• [x ] My entry follows the Codecademy Docs style guide.
• [x ] My changes generate no new warnings.
• [x ] I have performed a self-review of my own writing and code.
• [x ] I have checked my entry and corrected any misspellings.
• [x ] I have made corresponding changes to the documentation if needed.
• [x ] I have confirmed my changes are not being pushed from my forked main branch.
• [x ] I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• [x ] I have linked any issues that are relevant to this PR in the Issues Solved section.