CAMEL-23284: Fix Pipe Kamelet properties with {{placeholder}} being URL-encoded

[Croway]

Summary

When a Pipe YAML uses {{placeholder}} in Kamelet source/sink properties, the curly braces are URL-encoded to %7B%7B...%7D%7D by URISupport.createQueryString(), preventing Camel's property placeholder resolver from recognizing them.

Reproducer:

apiVersion: camel.apache.org/v1
kind: Pipe
metadata:
  name: placeholder-bug
spec:
  source:
    ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1
      name: timer-source
    properties:
      message: "{{my.message}}"
  sink:
    uri: "log:result"

camel run pipe.yaml --prop=my.message="Hello Camel"
# Expected: logs "Hello Camel"
# Actual:   logs "%7B%7Bmy.message%7D%7D"

Root cause: extractCamelEndpointUri() in YamlRoutesBuilderLoader calls URISupport.createQueryString(params) which URL-encodes {{ to %7B%7B and }} to %7D%7D. The encoding itself is correct and necessary for special characters, but property placeholder double-braces must be preserved.

Fix: After creating the query string, restore %7B%7B → {{ and %7D%7D → }} so Camel's property placeholder resolver can find them.

Jira: https://issues.apache.org/jira/browse/CAMEL-23284

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🧪 CI tested the following changed modules:

• dsl/camel-yaml-dsl/camel-yaml-dsl

All tested modules (34 modules)

• Camel :: Coverage
• Camel :: Coverage [pom]
• Camel :: JBang :: Core
• Camel :: JBang :: Core [jar]
• Camel :: JBang :: Integration tests
• Camel :: JBang :: Integration tests [jar]
• Camel :: JBang :: MCP
• Camel :: JBang :: MCP [jar]
• Camel :: JBang :: Main
• Camel :: JBang :: Main [jar]
• Camel :: JBang :: Plugin :: Edit
• Camel :: JBang :: Plugin :: Edit [jar]
• Camel :: JBang :: Plugin :: Generate
• Camel :: JBang :: Plugin :: Generate [jar]
• Camel :: JBang :: Plugin :: Kubernetes
• Camel :: JBang :: Plugin :: Kubernetes [jar]
• Camel :: JBang :: Plugin :: Route Parser
• Camel :: JBang :: Plugin :: Route Parser [jar]
• Camel :: JBang :: Plugin :: Testing
• Camel :: JBang :: Plugin :: Testing [jar]
• Camel :: JBang :: Plugin :: Validate
• Camel :: JBang :: Plugin :: Validate [jar]
• Camel :: Kamelet Main
• Camel :: Kamelet Main [jar]
• Camel :: Launcher
• Camel :: Launcher [jar]
• Camel :: Launcher :: Container
• Camel :: Launcher :: Container [pom]
• Camel :: YAML DSL
• Camel :: YAML DSL [jar]
• Camel :: YAML DSL :: Validator
• Camel :: YAML DSL :: Validator [jar]
• Camel :: YAML DSL :: Validator Maven Plugin
• Camel :: YAML DSL :: Validator Maven Plugin [maven-plugin]