pkg/tfvars/libvirt/cache: Remove .gz suffix handling

[wking]

The new pipeline handles Content-Encoding gzip:

$ curl -LI --compressed https://releases-rhcos.svc.ci.openshift.org/storage/releases/maipo/47.73/redhat-coreos-maipo-47.73-qemu.qcow2
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.12.1
Date: Tue, 06 Nov 2018 20:55:06 GMT
Content-Type: text/html
Content-Length: 161
Location: https://d26v6vn1y7q7fv.cloudfront.net/releases/maipo/47.73/redhat-coreos-maipo-47.73-qemu.qcow2
Set-Cookie: ...; path=/; HttpOnly; Secure

HTTP/1.1 200 OK
Content-Type: binary/octet-stream
Content-Length: 726878219
Connection: keep-alive
Date: Tue, 06 Nov 2018 20:23:37 GMT
Last-Modified: Tue, 06 Nov 2018 17:56:36 GMT
ETag: "021080ef3b515d2443be3749ebbb0b08-87"
Content-Encoding: gzip
Accept-Ranges: bytes
Server: AmazonS3
Age: 1890
X-Cache: Hit from cloudfront
Via: 1.1 d85d7507ed6501757cfe600c02a26c7d.cloudfront.net (CloudFront)
X-Amz-Cf-Id: ...

so we can rely on Go's default compression handling. See DisableCompression, which defaults to false. To confirm the default handling, try to retrieve from a local server:

$ export OPENSHIFT_INSTALL_LIBVIRT_IMAGE=http://localhost:8080/example.qcow
$ openshift-install --dir=wking create cluster
INFO Fetching OS image...
FATAL Error executing openshift-install: failed to fetch Terraform Variables: failed to generate asset "Terraform Variables": failed to get Tfvars: failed to use cached libvirt image: Get http://localhost:8080/example.qcow: EOF

In another terminal, I was using Ncat as a dummy server to capture request headers:

$ nc -l -p 8080 </dev/null
GET /example.qcow HTTP/1.1
Host: localhost:8080
User-Agent: Go-http-client/1.1
Accept-Encoding: gzip

This commit drops the now-unnecessary suffix handling from 7abe94d (#280).

[abhinavdahiya]

/lgtm

[abhinavdahiya]

/lgtm

[openshift-ci-robot]

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[wking]

e2e-aws:

* module.vpc.aws_eip.nat_eip[4]: 1 error(s) occurred:

* aws_eip.nat_eip.4: Error creating EIP: AddressLimitExceeded: The maximum number of addresses has been reached.
	status code: 400, request id: ca098949-60ae-4fd4-882d-9f4527f1561f

I'll run my cleanup script.

[wking]

/retest