Remove `test_apf_drop_ethercat` multi-devices test

This test added from CTS-15_r2, new test cases should be punted to CTS-16 release.

Bug: 368983928
Test: test-only change
Merged-In: Ic5aecbf316f150c5b975e5dfe6cd110bd42c2135
Change-Id: I4f9cc932a979048700898938d6d9c70d8456beb8
1 file changed