`ppr`: fix issue with `extra_build_args` initialization #2692

Job	Run time
Flake8 tests	18s
Java Spotless check	25s
documentation	15s
Build test APP [ ${{ matrix.runs_on }} \| ${{ matrix.bootstrap.name }} ]	-1s
Build test APP [ ${{ matrix.runs_on }} \| ${{ matrix.bootstrap.name }} ]	-1s
Test updated recipes for arch ${{ matrix.android_arch }} [ ubuntu-latest ]	-1s
Pytest [Python ${{ matrix.python-version }} \| ${{ matrix.os }}]	-1s
Test updated recipes for arch ${{ matrix.android_arch }} [ ${{ matrix.runs_on }} ]	-1s
coveralls_finish	-1s
Run App on Emulator	-1s
	51s

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