Handle a HostSystem with missing product vendor

[agrare]

Handle the case where a HostSystem is missing summary.config.product.vendor.
We already set the vmm_vendor to "unknown" if we do not recognize the vendor, but this will throw an exception if the attribute is completely missing:

     Failure/Error: vendor = product[:vendor].split(",").first.to_s.downcase
     
     NoMethodError:
       undefined method `split' for nil:NilClass
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/parser/host_system.rb:116:in `parse_host_system_product'
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/parser.rb:205:in `parse_host_system'
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/parser.rb:28:in `parse'
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/collector.rb:252:in `block in parse_updates'
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/collector.rb:242:in `each'
     # ./app/models/manageiq/providers/vmware/infra_manager/inventory/collector.rb:242:in `parse_updates'

[miq-bot]

Checked commit agrare@40e9e19 with ruby 2.6.10, rubocop 1.28.2, haml-lint 0.35.0, and yamllint
2 files checked, 0 offenses detected
Everything looks fine. 👍

[Fryguy]

Backported to quinteros in commit 5829a26.

commit 5829a26588fb37835e83112e3c73559c53b88e37
Author: Jason Frey <[email protected]>
Date:   Mon Sep 18 15:28:11 2023 -0400

    Merge pull request #882 from agrare/fix_host_parser_no_vendor
    
    Handle a HostSystem with missing product vendor
    
    (cherry picked from commit 3bdb9cd706e5cc678bf760d3dcb6f6fe0d94911a)