Update manage-self-service-purchases-users.md

[mihart]

removed mentions of trials since this article is about purchases. We link from PBI and we noticed that including trials isn't relevant here.

[learn-build-service-prod]

Learn Build status updates of commit 2f48df7:

✅ Validation status: passed

File	Status	Preview URL	Details
microsoft-365/commerce/subscriptions/manage-self-service-purchases-users.md	✅Succeeded

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[mihart]

#sign-off

[learn-build-service-prod]

Learn Build status updates of commit 3099b7a:

✅ Validation status: passed

File	Status	Preview URL	Details
microsoft-365/commerce/subscriptions/manage-self-service-purchases-users.md	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel