test: Change "make test-stem" so it only runs the stem tests that use…

[teor2345]

… tor

This change makes test-stem faster and more reliable.

Use "make test-stem-full" to run all of stem's tests.

Closes ticket 31554.

[coveralls]

Pull Request Test Coverage Report for Build 5982

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 12 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.02%) to 60.27%

---

Files with Coverage Reduction	New Missed Lines	%
src/feature/dirauth/shared_random.c	3	85.64%
src/feature/dirauth/dirvote.c	9	64.79%

Totals
Change from base Build 5964:	-0.02%
Covered Lines:	42857
Relevant Lines:	71108

---

💛 - Coveralls