NIFI-15228 Corrected expected result of EL repeat function when the exact number to repeat is the string's length.

Author: dan-s1

nifi-docs/src/main/asciidoc/expression-language-guide.adoc

@@ -1205,7 +1205,7 @@ then the following Expressions will result in the following values:
 | `${str:repeat(1)}` | `abc`
 | `${str:repeat(2)}` | `abcabc`
 | `${str:repeat(1,2)}` | `abc` or `abcabc` (at random)
-| `${str:repeat( ${str:length()} )}` | `abc` or `abcabc` or `abcabcabc` (at random)
+| `${str:repeat( ${str:length()} )}` | `abcabcabc`
 |================================================================