DOCS-708: remove jet-start.sh links

docs/modules/ROOT/pages/capacity-planning.adoc

@@ -578,8 +578,7 @@ larger event journal can be used to stretch the error window.
 
 == Garbage Collection Considerations
 
-Based on an https://jet-start.sh/blog/2020/06/09/jdk-gc-benchmarks-part1[extensive testing campaign]
-we performed in June-August 2020, we extracted some points of advice on how to choose
+Based on an extensive testing, we extracted some points of advice on how to choose
 the right JDK/GC (Garbage Collection) combination and how to tune your setup to the workload
 of your Hazelcast data pipeline.
 
@@ -608,7 +607,7 @@ pause length under such conditions.
 If you aim for very low latencies (anything below 10 ms), you can
 achieve it with G1 as well, but you will probably have to use the
 `-XX:MaxNewSize` flag in order to constrain the Minor GC pause duration.
-In our https://jet-start.sh/blog/2020/08/05/gc-tuning-for-jet[test] we found the values
+In our test we found the values
 `100m`-`200m` to work best over our range of throughputs, lower values
 being better for lower throughputs.
 

docs/modules/migrate/pages/upgrading-from-jet.adoc

@@ -68,7 +68,7 @@ The following methods for configuring the underlying IMDG instance of Jet have b
 - `configureHazelcast()`
 - `setHazelcastConfig()`
 
-If you used the link:https://jet-start.sh/javadoc/4.5/com/hazelcast/jet/config/JetConfig.html[`JetConfig` object] to configure IMDG, you should replace instances of `JetConfig` with link:https://docs.hazelcast.org/docs/{full-version}/javadoc/com/hazelcast/config/Config.html[`Config`].
+If you used the `JetConfig` object to configure IMDG, you should replace instances of `JetConfig` with link:https://docs.hazelcast.org/docs/{full-version}/javadoc/com/hazelcast/config/Config.html[`Config`].
 
 [tabs] 
 ==== 
@@ -99,7 +99,7 @@ HazelcastInstance hz = Hazelcast.newHazelcastInstance(config);
 
 === InstanceConfig
 
-The link:https://jet-start.sh/javadoc/4.5/com/hazelcast/jet/config/InstanceConfig.html[`InstanceConfig` object] has been deprecated and all its methods have been added to the `JetConfig` object.
+The `InstanceConfig` object has been deprecated and all its methods have been added to the `JetConfig` object.
 
 [tabs] 
 ==== 
@@ -154,7 +154,7 @@ All configuration loader methods have been moved from the `JetConfig` object to
 
 === Jet Properties
 
-In the Java API, properties in the link:https://jet-start.sh/javadoc/4.5/com/hazelcast/jet/core/JetProperties.html[`JetProperties` object] have been merged into the link:https://docs.hazelcast.org/docs/{full-version}/javadoc/com/hazelcast/spi/properties/ClusterProperty.html[`ClusterProperty` object].
+In the Java API, properties in the `JetProperties` object have been merged into the link:https://docs.hazelcast.org/docs/{full-version}/javadoc/com/hazelcast/spi/properties/ClusterProperty.html[`ClusterProperty` object].
 
 The following Jet properties have been removed: