Update dockerfiles to use yarn install instead npm install

Author: olafurpg

Dockerfile

@@ -1,4 +1,4 @@
-FROM sourcegraph/src-cli:3.39.1@sha256:418225d34348a80613a6a20c6c0203d95a74a33adc6fb6e6f45af84ff60beff0 AS src-cli
+FROM sourcegraph/src-cli:3.40.0
 
 # Keep in sync with Dockerfile.autoindex
 FROM node:17.7.1-alpine3.14@sha256:cbb62fa2f740959b173b180e4806a5e479fbbd7a20072c3d6b4283bf2b9951d1
@@ -9,6 +9,8 @@ RUN apk add --no-cache git
 
 COPY --from=src-cli /usr/bin/src /usr/bin
 
-RUN npm install -g @sourcegraph/scip-typescript@${TAG}
+RUN npm install --global yarn
+
+RUN yarn global add @sourcegraph/scip-typescript@${TAG}
 
 CMD ["/bin/sh"]

Dockerfile.autoindex

@@ -11,6 +11,8 @@ COPY --from=src-cli /usr/bin/src /usr/bin
 
 RUN echo 'scip-typescript "$@" --no-progress-bar' > /usr/bin/scip-typescript-autoindex && chmod +x /usr/bin/scip-typescript-autoindex
 
-RUN npm install --global n@latest @sourcegraph/scip-typescript@latest
+RUN npm install --global yarn
+
+RUN yarn global add @sourcegraph/scip-typescript@${TAG}
 
 CMD ["/bin/sh"]