DC API does not return failure while creating a strategy with no steps

[Jessica Castelino]

Brief Description
-----------------
After creating the strategy to a subcloud group and there is no Steps available, is possible to apply it without an error message.

Severity
-----------------
Minor

Steps to Reproduce
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Create a strategy.
Check there are no steps available.
Apply the strategy

Expected Behavior
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Apply strategy button is not available.

Actual Behavior
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Apply strategy button is available. The strategy applies. An error message is displayed

Reproducibility
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100%

System Configuration
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Distributed Cloud

Test Activity
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Testing in Sprint

Branch/Pull Time/Commit
-----------------
2021-09-13_00-00-10

Last Pass
---------
N/A

Workaround
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Check "dcmanager strategy-step-list" and if there are no steps, don't apply the strategy

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/distcloud/+/816536

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/distcloud/+/816536
Committed: https://opendev.org/starlingx/distcloud/commit/952ad5fc7b75df4f51c7f603d3e3c6bcd071af0e
Submitter: "Zuul (22348)"
Branch: master

commit 952ad5fc7b75df4f51c7f603d3e3c6bcd071af0e
Author: Jessica Castelino <email address hidden>
Date: Mon Nov 1 09:53:00 2021 -0400

    Raise exception when a strategy is created with no steps

    It is possible for a user to create and apply a strategy with no
    strategy steps. This commit raises an exception in such a scenario
    to make it more intuitive and user friendly.

    Additionally, this commit also fixes the stage numbering.

    Test Plan:
    1) Strategy raises exception when there are no steps
    2) Strategy numbering starts with 1 for all type of strategies

    Change-Id: I2b9c0a757129aa165512718cb93ccdf31d1b69dc
    Signed-off-by: Jessica Castelino <email address hidden>
    Closes-Bug: 1949478