fix(e2e): fix WF18 Suite Setup tag separator to two spaces

Robot Framework requires ≥2 spaces (or a tab) to separate multiple
values in a [Tags] setting. The WF18 Suite Setup keyword had a single
space between tdd_issue and tdd_issue_4188, causing RF to parse them
as a single tag with a space in its name rather than two distinct tags.
The tdd_expected_fail_listener validates that tdd_issue_N requires a
standalone tdd_issue tag — the single-space bug was silently breaking
that validation.

Fix: change `tdd_issue tdd_issue_4188` to `tdd_issue    tdd_issue_4188`
(four-space separator, matching the rest of the file's style).

ISSUES CLOSED: #10815

robot/e2e/wf18_container_clone.robot

@@ -30,7 +30,7 @@ ${PROJECT_PREFIX}    local/wf18-clone-proj
 WF18 Suite Setup
   [Documentation]    E2E Suite Setup plus unique suffix generation and dynamic
   ...    actor selection for WF18 tests.
-  [Tags]    tdd_issue tdd_issue_4188
+  [Tags]    tdd_issue    tdd_issue_4188
   E2E Suite Setup
   # Initialise the workspace so CLI commands work.
   ${init}=    Run CleverAgents Command    init --force --yes