Update Bazel to 6.2.0 and remove bazel install scripts (#452)

## What is the goal of this PR?

We update the `.bazelversion` to 6.2.0 and remove the bazel install scripts. CI installations that want to use Bazel should instead download and use Bazelisk to align with the rest of the organisation's Bazel usage.

## What are the changes implemented in this PR?

* Update bazelversion to 6.2.0
* Remove bazel install scripts

Author: flyingsilverfin

.bazelversion

@@ -1 +1 @@
-5.1.1
+6.2.0

tool/bazelinstall/BUILD

@@ -1,3 +1,3 @@
 package(default_visibility = ["//visibility:public"])
 
-exports_files([ "linux.sh", "mac.sh", "remote_cache_setup.sh" ])
+exports_files([ "remote_cache_setup.sh" ])