Revert "Minor changes due to SE-0130: Replace String.init(repeating: Character, count: Int) by String.init(repeating: Sttring, count: Int)"

This reverts commit 61ba9dd.

Pushed to early. In needs to be pushed at the same time with a
corresponding commit on apple/swift.

Author: swiftix

Tests/Basic/OutputByteStreamPerfTests.swift

@@ -129,7 +129,7 @@ class OutputByteStreamPerfTests: XCTestCase {
 
     func test1MBOf16ByteStrings_X10() {
         // Test writing 1MB worth of 16 byte strings.
-        let string16 = String(repeating: "X", count: 1 << 4)
+        let string16 = String(repeating: Character("X"), count: 1 << 4)
 
         measure {
             for _ in 0..<10 {
@@ -144,7 +144,7 @@ class OutputByteStreamPerfTests: XCTestCase {
 
     func test1MBOf1KByteStrings_X100() {
         // Test writing 1MB worth of 1K byte strings.
-        let bytes1k = String(repeating: "X", count: 1 << 10)
+        let bytes1k = String(repeating: Character("X"), count: 1 << 10)
 
         measure {
             for _ in 0..<100 {
@@ -159,7 +159,7 @@ class OutputByteStreamPerfTests: XCTestCase {
 
     func test1MBOfJSONEncoded16ByteStrings_X10() {
         // Test writing 1MB worth of JSON encoded 16 byte strings.
-        let string16 = String(repeating: "X", count: 1 << 4)
+        let string16 = String(repeating: Character("X"), count: 1 << 4)
 
         measure {
             for _ in 0..<10 {

Tests/POSIX/ReaddirTests.swift

@@ -46,7 +46,7 @@ class ReaddirTests: XCTestCase {
                 }
             }
             s.d_namlen = UInt16(n)
-            XCTAssertEqual(s.name, String(repeating: "A", count: n))
+            XCTAssertEqual(s.name, String(repeating: Character("A"), count: n))
         }
     }