ci: quick-build profile skip shading (#14046)

Seeing this weird issue in the enforcer plugin:
```
19:50:20:126 [ERROR] Could not acquire shared lock for artifacts: io.grpc:grpc-api:jar:1.82.3, com.google.code.findbugs:jsr305:jar:3.0.2, com.google.errorprone:error_prone_annotations:jar:2.48.0, io.grpc:grpc-stub:jar:1.82.3, ... in 900 SECONDS; consider using 'aether.syncContext.named.time' property to increase lock timeout to a value that fits your environment
19:50:20:126 [ERROR] org.eclipse.aether.SyncContext$FailedToAcquireLockException: Could not acquire shared lock for artifacts: ... in 900 SECONDS
```

Gemini is suggesting that not shading may end up speeding up some of the
longer to build modules:
- GAPIC Showcase Client: 16:28 min
- GAPIC Generator Java: 16:14 min

Try it out to see if running in the CIs via `quick-build` profile can
help. Shading will continue to be run, but only skipped in the
quick-build profile.

EDIT: Looks like we have to shade the generator for now

Author: lqiu96

google-cloud-pom-parent/pom.xml

@@ -22,6 +22,9 @@
   <properties>
     <skipUnitTests>false</skipUnitTests>
     <checkstyle.header.file>java.header</checkstyle.header.file>
+    <!-- maven-shade-plugin does not define a built-in user property for its skip parameter;
+         shade.skip is declared here and mapped in shaded modules to allow quick-build to toggle it off. -->
+    <shade.skip>false</shade.skip>
   </properties>
 
   <developers>
@@ -72,6 +75,7 @@
         <fmt.skip>true</fmt.skip>
         <flatten.skip>true</flatten.skip>
         <mdep.analyze.skip>true</mdep.analyze.skip>
+        <shade.skip>true</shade.skip>
       </properties>
     </profile>
     <profile>

java-bigquery/benchmark/pom.xml

@@ -61,6 +61,7 @@
               <goal>shade</goal>
             </goals>
             <configuration>
+              <skip>${shade.skip}</skip>
               <finalName>${uberjar.name}</finalName>
               <transformers>
                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">

java-bigtable/pom.xml

@@ -286,6 +286,9 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
                 <version>3.6.0</version>
+                <configuration>
+                    <skip>${shade.skip}</skip>
+                </configuration>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>

java-bigtable/test-proxy/pom.xml

@@ -158,6 +158,7 @@
                 <goal>shade</goal>
               </goals>
               <configuration>
+                <skip>${shade.skip}</skip>
                 <filters>
                   <filter>
                     <artifact>*:*</artifact>

java-cloud-bom/pom.xml

@@ -29,6 +29,9 @@
 
   <properties>
     <enforcer.skip>true</enforcer.skip>
+    <!-- maven-shade-plugin does not define a built-in user property for its skip parameter;
+         shade.skip is declared here and mapped in shaded modules to allow quick-build to toggle it off. -->
+    <shade.skip>false</shade.skip>
   </properties>
 
   <modules>
@@ -116,6 +119,7 @@
         <fmt.skip>true</fmt.skip>
         <flatten.skip>true</flatten.skip>
         <mdep.analyze.skip>true</mdep.analyze.skip>
+        <shade.skip>true</shade.skip>
       </properties>
     </profile>
     <profile>

java-spanner-jdbc/pom.xml

@@ -275,6 +275,7 @@
               <goal>shade</goal>
             </goals>
             <configuration>
+              <skip>${shade.skip}</skip>
               <createSourcesJar>true</createSourcesJar>
               <shadeSourcesContent>true</shadeSourcesContent>
               <shadedArtifactAttached>true</shadedArtifactAttached>

java-storage-nio/google-cloud-nio/pom.xml

@@ -129,6 +129,7 @@
           </dependency>
         </dependencies>
         <configuration>
+          <skip>${shade.skip}</skip>
           <shadedArtifactAttached>true</shadedArtifactAttached>
           <relocations>
             <relocation>

java-storage/storage-shared-benchmarking/pom.xml

@@ -65,6 +65,7 @@
               <goal>shade</goal>
             </goals>
             <configuration>
+              <skip>${shade.skip}</skip>
               <finalName>${uberjar.name}</finalName>
               <transformers>
                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">