services: Don't try to list/cleanup templates when OVN doesn't suppor…

[dceara]

…t that.

Spotted in upstream ovn-org/ovn CI when running against ovn versions <=22.09 which don't support component templates:

https://github.com/ovn-org/ovn/actions/runs/4628617882

Reported error:
failed to sync chassis: error: failed to get template var list: error:
Wrong parameter type (*nbdb.ChassisTemplateVar): Model not found in
Database Model

Fixes: 4b3475a ("services: Use OVN template load balancers for NodePort services.")

[dceara]

FYI @tssurya @flavio-fernandes @trozet this still fails because libovsdb refuses to connect to an old database (that doesn't contain the chassis_template_var table). I thought libovsdb was enhanced to support that, do you know what happened?

E0406 15:45:54.400748      56 ovnkube.go:369] error when trying to initialize libovsdb NB client: failed to connect to tcp:10.89.0.104:6641: database OVN_Northbound validation error (3): database model contains a model for table Chassis_Template_Var that does not exist in schema. Mapper Error. Object type nbdb.LogicalSwitchPort contains field MirrorRules ([]string) ovs tag mirror_rules: Column does not exist in schema. database model contains a model for table Mirror that does not exist in schema

[flavio-fernandes]

heh, I wonder if you need this PR merged first:
#3507

[coveralls]

Coverage: 52.876% (-0.03%) from 52.905% when pulling 2a89def on dceara:fix-no-template-support into 0254d0f on ovn-org:master.

[dceara]

heh, I wonder if you need this PR merged first: #3507

@flavio-fernandes I don't know. Does that enable support to connect to a database that has an older schema (missing some tables) compared to the schema that was used to generate the model?

[flavio-fernandes]

/lgtm

[dceara]

FYI @tssurya @flavio-fernandes @trozet this still fails because libovsdb refuses to connect to an old database (that doesn't contain the chassis_template_var table). I thought libovsdb was enhanced to support that, do you know what happened?

E0406 15:45:54.400748      56 ovnkube.go:369] error when trying to initialize libovsdb NB client: failed to connect to tcp:10.89.0.104:6641: database OVN_Northbound validation error (3): database model contains a model for table Chassis_Template_Var that does not exist in schema. Mapper Error. Object type nbdb.LogicalSwitchPort contains field MirrorRules ([]string) ovs tag mirror_rules: Column does not exist in schema. database model contains a model for table Mirror that does not exist in schema

In a private discussion @trozet pointed out that "older libovsdb should be able to connect to newer OVN schema". So that explains why i'm getting the above when trying to run against ovn 22.09.

Assuming that in the future libovsdb will be able "to connect to older OVN schema", the PR is still needed. If not, we might as well remove the useTemplate/svcTemplateSupport variables all together as they don't really make much sense.

[dceara]

Known CI failure: [Fail] Load Balancer Service Tests with MetalLB [It] Should ensure load balancer service works with 0 node ports when ETP=local

[dceara]

/retest-failed