[MNG-6829] Replace StringUtils#isEmpty(String) and #isNotEmpty(String)

[timtebeek]

Continuation of https://issues.apache.org/jira/browse/MNG-6829

Review requested of @elharo

Use this link to re-run the recipe: https://public.moderne.io/recipes/org.openrewrite.java.migrate.apache.commons.lang.IsNotEmptyToJdk?organizationId=QXBhY2hlIE1hdmVu

[elharo]

CI might be broken:

gpg: can't connect to the agent: Invalid value passed to IPC
gpg: error: GnuPG agent unusable. Please check that a GnuPG agent can be started.
gpg: migration aborted
gpg: can't connect to the agent: Invalid value passed to IPC
[GNUPG:] KEY_CONSIDERED CD251351B3EC94057BC44FD683CAA88765254A26 0
gpg: can't connect to the agent: Invalid value passed to IPC
[GNUPG:] INV_SGNR 0
gpg: keydb_search failed: No agent running
gpg: no default secret key: No agent running
[GNUPG:] FAILURE sign 33554509
gpg: signing failed: No agent running
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 19.465 s
[INFO] Finished at: 2023-05-14T17:02:16Z
[INFO] ------------------------------------------------------------------------
Error: Failed to execute goal org.apache.maven.plugins:maven-gpg-plugin:3.1.1-SNAPSHOT:sign (sign-artifacts) on project test: Exit code: 2 -> [Help 1]

[timtebeek]

Build issues replicated in #51 ; waiting for that to be resolved before we try again here.

[timtebeek]

@slachiewicz Thanks very much for seeing my PRs through; I think this is the very last of the first batch of PRs I did, and I hope to do a few more soon. Any chance we can merge this one too?