folks-sync-only: Drop testcase, obsolete

This testcase is meant to test a custom libfolks feature we carried downstream Aand that was proposed upstream and WONTFIX'ed in https://bugzilla.gnome.org/show_bug.cgi?id=741643

We're thus considering that this testcase does not bring any value to the project and is rather an hindrance since:

• the actual use-case for the feature is not really documented
• the implementation is problematic and has major architectural issues
• a proper solution would involve doing it in EDS rather than libfolks

No replacement is planned since contacts management via libfolks is not in the current priorities.

test-cases/folks-sync-only.yaml

-metadata:
-  name: folks-sync-only
-  format: "Apertis Test Definition 1.0"
-  image-types:
-    sdk:     [ amd64 ]
-  image-deployment:
-    - APT
-  type: unit
-  exec-type: automated
-  priority: medium
-  maintainer: "Apertis Project"
-  description: "Test SYNCHRONIZE_ONLY flag for persona stores in Folks."
-
-  expected:
-    - "The output should show PASSED or FAILED, similar to this:"
-    - |
-        >folks-extended-info: PASSED
-
-install:
-  deps:
-    - chaiwala-tests
-    - ofono-tests
-    - ofono-phonesim
-    - libfolks-ofono25
-  git-repos:
-    - url: https://gitlab.apertis.org/infrastructure/apertis-tests.git
-      branch: 'apertis/v2019dev0'
-
-run:
-  steps:
-    - "# Enter test directory:"
-    - cd apertis-tests
-    - "# Execute the following command:"
-    - common/run-test-in-systemd --user=user folks/folks-sync-only.sh
-
-parse:
-  fixupdict:
-    FAILED: fail
-    PASSED: pass
-    FAIL: fail
-    PASS: pass
-    SKIP: skip
-    UNKNOWN: unknown
-  pattern: '^(?P<test_case_id>[a-zA-Z0-9_\-\./]+):\s*(?P<result>PASSED|PASS|pass|FAILED|FAIL|fail|SKIP|skip|UNKNOWN|unknown)$'