refact: combine two filter conditions into one (#1241)

to reduce the overhead of filtering proposals.

Author: rubenporras

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/completion/LSContentAssistProcessor.java

@@ -271,9 +271,8 @@ private static List<ICompletionProposal> toProposals(IDocument document, int off
 				.filter(proposal -> {
 					// Stop the compute of ICompletionProposal if the completion has been cancelled
 					cancelChecker.checkCanceled();
-					return true;
-				}).filter(proposal -> proposal.validate(document, offset, null)) //
-				.map(ICompletionProposal.class::cast)
+					return proposal.validate(document, offset, null);
+				}).map(ICompletionProposal.class::cast)
 				.toList();
 	}