[BUG] longhorn-engine image no longer contains longhorn-instance manager

[keithalucas]

Describe the bug
longhorn/longhorn-engine@0224acb removed longhorn-instance-manager from the longhorn-engine image. longhorn-instance-manager is used by the launch-simple-file and launch-simple-longhorn scripts in /usr/local/bin.

To Reproduce
Steps to reproduce the behavior:

1. docker image pull longhornio/longhorn-engine:v1.1.2
2. docker run -it longhornio/longhorn-engine:v1.1.2 ls /usr/local/bin/
3. See that longhorn-instance-manager isn't in the output.

Expected behavior
longhorn-instance-manager should be in /usr/local/bin in order for launch-simple-file and launch-simple-longhorn to work.

Log
N/A

Environment:

• Longhorn version: v1.1.2
• Installation method (e.g. Rancher Catalog App/Helm/Kubectl): N/A
• Kubernetes distro (e.g. RKE/K3s/EKS/OpenShift) and version: N/A
  • Number of management node in the cluster: N/A
  • Number of worker node in the cluster: N/A
• Node config
  • OS type and version: N/A
  • CPU per node: N/A
  • Memory per node: N/A
  • Disk type(e.g. SSD/NVMe): N/A
  • Network bandwidth between the nodes: N/A
• Underlying Infrastructure (e.g. on AWS/GCE, EKS/GKE, VMWare/KVM, Baremetal): N/A
• Number of Longhorn volumes in the cluster: N/A

Additional context

[yasker]

Also, https://longhorn.io/docs/1.1.2/advanced-resources/data-recovery/export-from-replica/ won't work for v1.1.2 due to launch-simple-longhorn won't work.

[khushboo-rancher]

Verified with master-head 07/27/2021 and v1.1.3-head 07/27/2021

Validation - Pass

Validated with launch-simple-longhorn, It worked with master-head and v1.1.3-head

> docker run -it longhornio/longhorn-engine:master-head ls /usr/local/bin/
engine-manager	   launch-simple-file	   longhorn
grpc_health_probe  launch-simple-longhorn  longhorn-instance-manager

> docker run -it longhornio/longhorn-engine:v1.1.3-head ls /usr/local/bin/
engine-manager	   launch-simple-file	   longhorn
grpc_health_probe  launch-simple-longhorn  longhorn-instance-manager