ACCUMULO-4703 Use formatter-maven-plugin 2.5.0

Use latest formatter and impsort plugins, which set preqrequisites
correctly; also fix previous build breakage on older versions of Maven
by separating out minimum requirements to execute the
accumulo-maven-plugin (runs with 3.2.5+) from the minimum requirements
to build the Accumulo project (builds with 3.0.5+).
diff --git a/pom.xml b/pom.xml
index dc0a687..628813a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,7 +27,7 @@
   <name>Apache Accumulo Maven Plugin</name>
   <description>An Apache Maven plugin for testing software against a test Apache Accumulo instance.</description>
   <prerequisites>
-    <maven>${maven.min-version}</maven>
+    <maven>${maven.plugin-version}</maven>
   </prerequisites>
   <dependencies>
     <dependency>