Bump upjet to v1.4.0

[ulucinar]

Description of your changes

Related with: #1311

This PR bumps the upjet dependency to v1.4.0 and generates the secret references under spec.initProvider API trees for the sensitive MR parameters.

spec.forProvider.user of the Broker.mq dependency is moved to spec.initProvider.user in the User.mq example manifest to ignore the desired set of broker users declared via the Broker.mq MR and to prevent a race between the Broker.mq & User.mq controllers on the (external) broker users. We now also do a late-initialization configuration for spec.forProvider.user of Broker.mq so that it will be late-initialized iff the spec.initProvider.user is not set. This configuration is done to prevent an "unintended" race condition between the aforementioned controllers in cases where the client of the Broker.mq API deliberately disables broker user lifecycle management by only setting spec.initProvider.user and leaving spec.forProvider.user unset.

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable to ensure this PR is ready for review.
• [ ] Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

• A successful uptest run for User.v1alpha1.mq has been registered here: https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/9223380910/
• A successful uptest run for ClusterAuth.eks has been registered here: https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/9223465142/
• A successful uptest run for Budget.budgets has been registered here: https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/9223714803
• A successful uptest run for Policy.iot has been registered here: https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/9223739185

[ulucinar]

/test-examples="examples/mq/v1alpha1/user.yaml"

[ulucinar]

/test-examples="examples/eks/v1beta1/clusterauth.yaml"

[turkenf]

/test-examples="examples/budgets/v1beta1/budget.yaml"

[turkenf]

/test-examples="examples/iot/v1beta1/policy.yaml"