azure: validation: machinepool: sort slice before comparing

[r4f4]

We cannot rely on any ordering from iterating over a Golang map. If we do, we might fail unit tests because the values we compare with are different:

 --- FAIL: TestValidateMachinePool (0.00s)
    --- FAIL: TestValidateMachinePool/securityType_set_to_ConfidentialVM_but_securityEncryptionType_is_invalid (0.00s)
        machinepool_test.go:610:
            	Error Trace:	/go/src/github.com/openshift/installer/pkg/types/azure/validation/machinepool_test.go:610
            	Error:      	Expect "test-path.defaultMachinePlatform.osDisk.securityProfile.securityEncryptionType: Unsupported value: "invalidSecurityEncryptionType": supported values: "DiskWithVMGuestState", "VMGuestStateOnly"" to match "^test-path.defaultMachinePlatform.osDisk.securityProfile.securityEncryptionType: Unsupported value: "invalidSecurityEncryptionType": supported values: "VMGuestStateOnly", "DiskWithVMGuestState"$"
            	Test:       	TestValidateMachinePool/securityType_set_to_ConfidentialVM_but_securityEncryptionType_is_invalid
FAIL

Using a sorted list resolves the problem.

[r4f4]

This test failed in #7283 (see https://prow.ci.openshift.org/view/gs/origin-ci-test/pr-logs/pull/openshift_installer/7283/pull-ci-openshift-installer-master-unit/1688947382537949184)

[jhixson74]

/test e2e-azure-ovn

[openshift-ci]

@r4f4: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-azurestack	5b048b2	link	false	/test e2e-azurestack
ci/prow/e2e-azure-ovn-shared-vpc	5b048b2	link	false	/test e2e-azure-ovn-shared-vpc

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[barbacbd]

/lgtm

[rna-afk]

/approve

[jhixson74]

/lgtm
/approve

[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD 0be5579 and 2 for PR HEAD 5b048b2 in total

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jhixson74, rna-afk

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[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD 69e6e6f and 1 for PR HEAD 5b048b2 in total

[openshift-ci]

/test remaining-required