Improve LCS client install steps

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Fix Version/s: 7.0.x
• Component/s: Connected Services (LCS)
• Labels: None
• Git Pull Request: https://github.com/jhinkey/liferay-docs/pull/358

Clarify LCS client install steps in LCS preconfiguration article:

• https://customer.liferay.com/documentation/7.0/deploy/-/official_documentation/deployment/lcs-preconfiguration

The LCS client that ships with DXP must be manually removed prior deploying the latest client. Also, add brief manual Marketplace installation steps for the LCS client.