[lldb] PopulatePrpsInfoTest can fail due to hardcoded priority value (#104617)

In implementing this test one of the assertions assumes that the
priority is the default in linux (0) but, evidently, some of the build
runners prioritize the test to, at least, 5. This ensures that
regardless of the priority the test passes by validating that its the
process's priority
```
fgrim@host001 :~/llvm-project/debug_build> nice -n 15 tools/lldb/unittests/Process/elf-core/ProcessElfCoreTests
[==========] Running 2 tests from 1 test suite.
[----------] Global test environment set-up.
[----------] 2 tests from ElfCoreTest
[ RUN      ] ElfCoreTest.PopulatePrpsInfoTest
[       OK ] ElfCoreTest.PopulatePrpsInfoTest (4 ms)
[ RUN      ] ElfCoreTest.PopulatePrStatusTest
[       OK ] ElfCoreTest.PopulatePrStatusTest (3 ms)
[----------] 2 tests from ElfCoreTest (7 ms total)

[----------] Global test environment tear-down
[==========] 2 tests from 1 test suite ran. (8 ms total)
[  PASSED  ] 2 tests.
===(10:03)===
fgrim@host001 :~/llvm-project/debug_build>
```

0 files changed, 0 insertions, 0 deletions