Update TestMultiValidationTokeFile token generation with no trailing …

…newline char

Description

The test does the following:
1.Randomly appends new-line character to the token value buffer
2. If #1 is done, it generates temp token file with buffer containing
   new-line character.
3. Also, it remember the original token for future validation
4. The code parse and read token-validation files and removes the new-line
   character as desired.

Failure in this case due to random buffer used to populate token value
contained newline character which was used for validation, however,
the file parse/read code as expected removed the newline character,
hence causing the mismatch.

Patch addresses the concern by ensuring test generated random
token-value has no trailing newline chars.

Testing

tests/fast/RandomUnitTests.toml -s 1355028229

fdbserver/RESTKmsConnector.actor.cpp

@@ -1264,8 +1264,17 @@ ACTOR Future<Void> testMultiValidationFileTokenFiles(Reference<RESTKmsConnectorC
 	state std::string tokenDetailsStr;
 	state bool newLineAppended = BUGGIFY ? true : false;
 
-	deterministicRandom()->randomBytes(mutateString(buff), tokenLen);
-	std::string token((char*)buff.begin(), tokenLen);
+	std::string token;
+	// Construct token-value buffer ensuring it doesn't have trailing new-line character.
+	loop {
+		deterministicRandom()->randomBytes(mutateString(buff), tokenLen);
+		token = std::string((char*)buff.begin(), tokenLen);
+		removeTrailingChar(token, '\n');
+		if (token.size() > 0) {
+			break;
+		}
+	}
+	tokenLen = token.size();
 	std::string tokenWithNewLine(token);
 	tokenWithNewLine.push_back('\n');