fix(i): Remove flakyness of AES decrypt test (sourcenetwork#3241)

## Relevant issue(s)

Resolves sourcenetwork#3240 

## Description

This PR fixes a flaky test where the modification of the cypher text was
supposed to cause it to fail decryption. The modification turned out to
sometime be the same as the actual cypher text.

crypto/aes_test.go

@@ -149,9 +149,10 @@ func TestDecryptAES(t *testing.T) {
 			errorContains:  "message authentication failed",
 		},
 		{
-			name:           "Tampered ciphertext",
-			nonce:          validNonce,
-			cipherText:     append([]byte{0}, validCiphertext[AESNonceSize+1:]...),
+			name:  "Tampered ciphertext",
+			nonce: validNonce,
+			// Flip a byte in the ciphertext to corrupt it.
+			cipherText:     append([]byte{^validCiphertext[AESNonceSize]}, validCiphertext[AESNonceSize+1:]...),
 			key:            validKey,
 			additionalData: validAAD,
 			expectError:    true,