fix(gapic-bom): remove handwritten storage boms

Remove `google-cloud-nio-bom` and `google-cloud-storage-bom` from `gapic-libraries-bom/pom.xml`.
These are handwritten clients that should be added to `java-cloud-bom/google-cloud-bom/pom.xml` instead.
Since `java-storage` and `java-storage-nio` are in the Kokoro `excluded_modules` list,
their snapshot BOMs are not installed to the local `.m2` repository during CI installation steps.
When `CreateBomCanaryProject` validates `gapic-libraries-bom/pom.xml`, the failure to resolve
these imported snapshot BOMs caused Maven to report missing versions for their underlying jars.

This reverts their accidental inclusion introduced in commits:
- 1da80e6 (google-cloud-nio-bom)
- 5a4afb5 (google-cloud-storage-bom)

Author: westarle

gapic-libraries-bom/pom.xml

@@ -957,13 +957,6 @@
         <type>pom</type>
         <scope>import</scope>
       </dependency>
-      <dependency>
-        <groupId>com.google.cloud</groupId>
-        <artifactId>google-cloud-nio-bom</artifactId>
-        <version>0.128.15-SNAPSHOT</version><!-- {x-version-update:google-cloud-nio:current} -->
-        <type>pom</type>
-        <scope>import</scope>
-      </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-notebooks-bom</artifactId>
@@ -1270,13 +1263,6 @@
         <type>pom</type>
         <scope>import</scope>
       </dependency>
-      <dependency>
-        <groupId>com.google.cloud</groupId>
-        <artifactId>google-cloud-storage-bom</artifactId>
-        <version>2.64.2-SNAPSHOT</version><!-- {x-version-update:google-cloud-storage:current} -->
-        <type>pom</type>
-        <scope>import</scope>
-      </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-storage-transfer-bom</artifactId>