tests: remove leftover test targets in test application makefiles

[aabadie]

Contribution description

This is removing leftover test targets in test applications. Found while cleaning up generated applications after running the full test-suite.

Testing procedure

• run make distclean > /dev/null from the riot directory
• with master, you get something like:

Makefile:11: warning: overriding recipe for target 'test'
...tests/cond_order/../../Makefile.include:568: warning: ignoring old recipe for target 'test'
/bin/sh: 1: Syntax error: Missing '))'
Makefile:41: warning: overriding recipe for target 'test'
...tests/pkg_cmsis-dsp/../../Makefile.include:568: warning: ignoring old recipe for target 'test'
Makefile:9: warning: overriding recipe for target 'test'
...tests/pkg_lora-serialization/../../Makefile.include:568: warning: ignoring old recipe for target 'test'

• with this PR, you now get something like:

/bin/sh: 1: Syntax error: Missing '))'

The syntax error comes from a bug with how the ROM_LEN is computed with kinetis based boards. I'll open a PR to fix this after this one.

Issues/PRs references

None

[cladmi]

There are indeed only this test file in these tests

$ ls tests/cond_order/tests/
01-run.py
$ ls tests/pkg_cmsis-dsp/tests/
01-run.py
$ ls tests/pkg_lora-serialization/tests/
01-run.py

For reference, it was added by #9567 where the tests scripts area automatically found.

[cladmi]

ACK I tested the tests are still run. The tested procedure also works with the error in master and only one message with this PR.
The commits could reference the PR deprecating defining tests but I will not block for this as I mentioned it in the PR. Keep them if you want.

@aabadie I let you merge like this or with updated commits as you want.

[aabadie]

I let you merge like this or with updated commits as you want.

Let's merge like this! Thanks for reviewing.