update filter example with what we use for tests (#7737)
update filter example with what we use for tests (#7737)

Description:

this forces the same workspace file we use for tests:

https://github.com/envoyproxy/envoy/blob/14c5371/ci/build_setup.sh#L75
to be pushed to the envoy-filter-example. this will allow not having
to file a manual PR to fix the build, such as:

envoyproxy/envoy-filter-example#95

Risk Level: Low
Testing: locally
Docs Changes: None
Release Notes: None

Signed-off-by: Cynthia Coan <69fb0556d9585ee9f65c6ae20b6c740f903508bc@instructure.com>
istio/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,eklitzke/envoy,eklitzke/envoy,istio/envoy,jrajahalme/envoy,eklitzke/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,eklitzke/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy,istio/envoy,istio/envoy,envoyproxy/envoy,lizan/envoy,eklitzke/envoy,envoyproxy/envoy-wasm,lizan/envoy,eklitzke/envoy,lizan/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,istio/envoy,jrajahalme/envoy,envoyproxy/envoy-wasm,istio/envoy,envoyproxy/envoy,jrajahalme/envoy,envoyproxy/envoy,lizan/envoy,lyft/envoy,istio/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,lyft/envoy,lyft/envoy,jrajahalme/envoy,jrajahalme/envoy