[C++][CI] Occasional timeout failures on arrow-compute-scalar-test

Sometimes C++ tests fail due to a timeout on `arrow-compute-scalar-test`:
```java

30/85 Test #29: arrow-compute-scalar-test .................***Timeout 300.04 sec
Running arrow-compute-scalar-test, redirecting output into /build/cpp/build/test-logs/arrow-compute-scalar-test.txt (attempt 1/1)
```
Job failure example:

I've realized that even when it run successfully it takes around 4 minutes (timeout is 5 minutes):
```java

32/85 Test #29: arrow-compute-scalar-test ................. Passed 229.77 sec
```
Should these tests be split?
```java

add_arrow_compute_test(scalar_test
                       SOURCES
                       scalar_arithmetic_test.cc
                       scalar_boolean_test.cc
                       scalar_cast_test.cc
                       scalar_compare_test.cc
                       scalar_if_else_test.cc
                       scalar_nested_test.cc
                       scalar_random_test.cc
                       scalar_set_lookup_test.cc
                       scalar_string_test.cc
                       scalar_temporal_test.cc
                       scalar_validity_test.cc
                       test_util.cc)
```

**Reporter**: [Raúl Cumplido](https://issues.apache.org/jira/browse/ARROW-17207) / @raulcd
**Assignee**: [Weston Pace](https://issues.apache.org/jira/browse/ARROW-17207) / @westonpace
#### PRs and other links:
- [GitHub Pull Request #14467](https://github.com/apache/arrow/pull/14467)

_{**Note**: *This issue was originally created as [ARROW-17207](https://issues.apache.org/jira/browse/ARROW-17207). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}