NIFI-16144 Removed redundant String operations

[dan-s1]

Summary

NIFI-16144

This PR removed unnecessary uses of

• String constructor with byte array from a ByteArrayOutputStreamwhen the toString method of ByteArrayOutputStream could be used.
• Use of String.substring in StringBuilder
• Use of two argument String.substring when the last index is the end index of the string
• String constructor indicating start and end of byte array when the start was 0 and end was length of the byte array

Tracking

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Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000
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Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files

[exceptionfactory]

Thanks @dan-s1