fix(sidekick/rust): Remove newline at EOF in subtemplate (googleapis#4027)

The newline is visible in generated code and breaks it.

Fixes googleapis#4026

Author: amanda-tarafa

internal/sidekick/rust/templates/common/client_method_samples/builder_fields.mustache

@@ -16,7 +16,6 @@ limitations under the License.
 Terminate each line in a comment so
 (a) we can read this code as each case is in a separate line,and
 (b) the newline is suppressed in the output to get tighter code.
-Also use no newline at the end of file so the the partials are all merged into a single line.
 }}{{#AIPStandardGetInfo}}{{!
 }}.set_{{ResourceNameRequestField.Codec.SetterName}}(resource_name){{!
 }}{{/AIPStandardGetInfo}}{{!
@@ -30,3 +29,6 @@ Also use no newline at the end of file so the the partials are all merged into a
 }}.set_{{ParentRequestField.Codec.SetterName}}(parent){{!
 }}{{/AIPStandardListInfo}}{{!
 }}{{^IsAIPStandard}}/* set fields */{{/IsAIPStandard}}
+{{!
+Use no newline at the end of file so the the partials are all merged into a single line.
+}}