Remove unsupported async_search parameters from rest-api-spec

[pquentin]

Partly reverts commit 2f8bb0b introduced in #117312.

@javanna pointed me to this comment that I had read but failed to fully take into account:

elasticsearch/x-pack/plugin/async-search/src/main/java/org/elasticsearch/xpack/search/RestSubmitAsyncSearchAction.java

Lines 60 to 63 in 2ed318f

	// for simplicity, we share parsing with ordinary search. That means a couple of unsupported parameters, like scroll
	// and pre_filter_shard_size get set to the search request although the REST spec don't list
	// them as supported. We rely on SubmitAsyncSearchRequest#validate to fail in case they are set.
	// Note that ccs_minimize_roundtrips is also set this way, which is a supported option.

And indeed three parameters raise an exception:

elasticsearch/x-pack/plugin/async-search/src/test/java/org/elasticsearch/xpack/search/SubmitAsyncSearchRequestTests.java

Lines 102 to 126 in 2ed318f

	public void testValidateKeepAlive() {
	SubmitAsyncSearchRequest req = new SubmitAsyncSearchRequest();
	req.setKeepAlive(TimeValue.timeValueMillis(randomIntBetween(1, 999)));
	ActionRequestValidationException exc = req.validate();
	assertNotNull(exc);
	assertThat(exc.validationErrors().size(), equalTo(1));
	assertThat(exc.validationErrors().get(0), containsString("[keep_alive]"));
	}
	public void testValidateSuggestOnly() {
	SubmitAsyncSearchRequest req = new SubmitAsyncSearchRequest();
	req.getSearchRequest().source(new SearchSourceBuilder().suggest(new SuggestBuilder()));
	ActionRequestValidationException exc = req.validate();
	assertNotNull(exc);
	assertThat(exc.validationErrors().size(), equalTo(1));
	assertThat(exc.validationErrors().get(0), containsString("suggest"));
	}
	public void testValidatePreFilterShardSize() {
	SubmitAsyncSearchRequest req = new SubmitAsyncSearchRequest();
	req.getSearchRequest().setPreFilterShardSize(randomIntBetween(2, Integer.MAX_VALUE));
	ActionRequestValidationException exc = req.validate();
	assertNotNull(exc);
	assertThat(exc.validationErrors().size(), equalTo(1));
	assertThat(exc.validationErrors().get(0), containsString("[pre_filter_shard_size]"));

However, I kept ccs_minimize_roundtrips which is explicitly supported (as stated in the comment too):

elasticsearch/x-pack/plugin/async-search/src/test/java/org/elasticsearch/xpack/search/SubmitAsyncSearchRequestTests.java

Lines 84 to 89 in 2ed318f

	public void testValidateCssMinimizeRoundtrips() {
	SubmitAsyncSearchRequest req = new SubmitAsyncSearchRequest();
	req.getSearchRequest().setCcsMinimizeRoundtrips(true);
	ActionRequestValidationException exc = req.validate();
	assertNull(exc);
	}

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)

[elasticsearchmachine]

💚 Backport successful

Status	Branch	Result
✅	8.17
✅	8.x