feat: (IAC-1063) Optimize Dockerfile

[jarpat]

Changes

In order to keep our Docker image as light as possible, opting not to install all the gcloud components as that drastically increases the image size and many of the components are irrelevant to the resources created by this project. This project now also makes use of google/cloud-sdk:xxx.0.0-alpine as the base image, which includes a smaller default set of gcloud components. On top of that we also install the gke-gcloud-auth-plugin, Cloud SQL Proxy, and the gcloud Alpha/Beta Commands. All the gcloud components necessary for interacting with the resources created by this project are installed by default.

If you require additional gcloud components to be present within the Docker image, you can set the INSTALL_COMPONENTS build-arg to a space separated list of components IDs.

The above is documented in DockerUsage.md and a small note could be included in the next release notes.

Some Stats:
viya4-iac-gcp:5.2.0 (before)

• 4.81GB on disk
• 1.83GB compressed size on repository

viya4-iac-gcp:IAC-1063 (after)

• 2.23GB on disk
• 619.01MB compressed size in repository

Tests

Scenario	Provider	K8s Version	Order	Cadence	Image	Notes
1	GCP	1.26.5-gke.1400	******	fast:2020	External	Terraform apply/destroy
2	GCP	1.26.5-gke.1400	******	fast:2020	Internal	Terraform apply/destroy
3	GCP	1.26.5-gke.1400	n/a	n/a	External	Installed additional components & test different binary entry points
4	GCP	1.26.5-gke.1400	n/a	n/a	Internal	Installed additional components & test different binary entry points