Remove Helidon gRPC client module

(merge 15.1.1-0 -> ce/15.1.1-0 118411)

[git-p4: depot-paths = "//dev/coherence-ce/release/coherence-ce-v15.1.1.0/": change = 118414]

Author: thegridman

prj/coherence-bom/pom.xml

@@ -165,11 +165,6 @@
         <artifactId>coherence-grpc-client-common</artifactId>
         <version>${project.version}</version>
       </dependency>
-      <dependency>
-        <groupId>${coherence.group.id}</groupId>
-        <artifactId>coherence-grpc-client-helidon</artifactId>
-        <version>${project.version}</version>
-      </dependency>
       <dependency>
         <groupId>${coherence.group.id}</groupId>
         <artifactId>coherence-hnsw</artifactId>