Fix NUCLEO_L452RE_P arduino pins

[multiplemonomials]

Summary of changes

Made this PR when running CI shield tests on NUCLEO_L452RE_P. Turns out that the Arduino pinmappings for this board are slightly wrong, in a way that was causing the CI tests to fail. This PR fixes it, and also makes two other small fixes.

Impact of changes

Migration actions required

Documentation

None

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Pull request type

[X] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[X] Tests / results supplied as part of this PR

Test run for L452RE available here: https://mbed-ce.github.io/mbed-ce-test-tools/tests/index.html

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