chore: remove unnecessary dep on guava in tools (#4221)

Change-Id: I52be2d2af5b10c37c3cdc791a45f14b17499f57f

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
- [ ] Make sure to open an issue as a [bug/issue](https://togithub.com/googleapis/java-bigtable-hbase/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> ☕️

If you write sample code, please follow the [samples format](
https://togithub.com/GoogleCloudPlatform/java-docs-samples/blob/main/SAMPLE_FORMAT.md).

Author: igorbernstein2

bigtable-hbase-1.x-parent/bigtable-hbase-1.x-tools/pom.xml

@@ -84,13 +84,6 @@
       <version>1.2.11</version>
       <scope>runtime</scope>
     </dependency>
-    <dependency>
-      <groupId>com.google.guava</groupId>
-      <artifactId>guava</artifactId>
-      <version>${guava.version}</version>
-      <!--  todo: align guava deps - we use repackaged guava in the main classes-->
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>

bigtable-hbase-1.x-parent/bigtable-hbase-1.x-tools/src/test/java/com/google/cloud/bigtable/hbase/tools/HBaseSchemaTransformerTest.java

@@ -22,7 +22,6 @@
 import com.google.bigtable.repackaged.com.google.gson.JsonObject;
 import com.google.cloud.bigtable.hbase.tools.ClusterSchemaDefinition.TableSchemaDefinition;
 import com.google.cloud.bigtable.hbase.tools.HBaseSchemaTranslator.JsonBasedSchemaTransformer;
-import com.google.common.collect.ImmutableMap;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.io.Writer;
@@ -88,8 +87,9 @@ public void testParseJsonTables() throws IOException {
     schemaTransformer = JsonBasedSchemaTransformer.newSchemaTransformerFromJsonFile(schemaFilePath);
 
     // Validate
-    Map<String, String> expectedTableMapping =
-        ImmutableMap.of("old-table", "new-table", "old-table-2", "random-table-2");
+    Map<String, String> expectedTableMapping = new HashMap<>();
+    expectedTableMapping.put("old-table", "new-table");
+    expectedTableMapping.put("old-table-2", "random-table-2");
     assertEquals(expectedTableMapping, schemaTransformer.tableNameMappings);
   }