Update EC2 Fleet example to use most recent LaunchTemplate version

[teabot]

Description of your changes

Updated the ec2_fleet example to use the more recent v1beta2 companion ec2_launch_template. Additionally fixed some formatting issues in the example that had caused some 'missing property' warnings.

I have:

• Read and followed Crossplane's contribution process.
• 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

uptest

export UPTEST_EXAMPLE_LIST=examples/ec2/v1beta1/fleet.yaml
make e2e

Result:

--- PASS: kuttl (72.98s)
    --- PASS: kuttl/harness (0.00s)
        --- PASS: kuttl/harness/case (72.20s)

[turkenf]

/test-examples="examples/ec2/v1beta1/fleet.yaml"

[turkenf]

Thank you @teabot, LGTM.