Avoid modifying the PATH for the python test suites #1454

Job	Run time
Compile the UX-less version of the app on Nano S+ for performance tests	1m 40s
Compilation for X, S+, Stax and Flex (nanox, $NANOX_SDK)	2m 31s
Compilation for X, S+, Stax and Flex (nanosp, $NANOSP_SDK)	1m 54s
Compilation for X, S+, Stax and Flex (stax, $STAX_SDK)	2m 7s
Compilation for X, S+, Stax and Flex (flex, $FLEX_SDK)	2m 1s
Performance report	3m 50s
Tests on mainnet (nanox)	46s
Tests on mainnet (nanosp)	45s
Tests with the JS library	1m 18s
Tests with the Python library and legacy Bitcoin app	56s
Tests on mainnet (stax)	43s
Tests for rust client library	1m 42s
Tests on mainnet (flex)	48s
Unit test	1m 25s
	22m 26s

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