[explorer.Dockerfile][build-configurations.yml] Removed --locked flag

Summary:
Copying the Cargo.lock file into the WORKDIR /usr/src/explorer Docker container was causing the compiler to complain as if the lock file required all the Cargo.toml in the workspace to be accessible as well. (we infer this as chronik/abc-rust-error is the first member in the root Cargo.toml workspace.

`(myenv) ➜ bitcoin-abc git:(docker_fix) ✗ docker build -f explorer.Dockerfile -t my-explorer-image .

• Building 1.5s (13/13) FINISHED docker:desktop-linux => [internal] load build definition from explorer.Dockerfile 0.0s => => transferring dockerfile: 910B 0.0s => [internal] load metadata for docker.io/library/rust:1.72-slim-bookworm 0.5s => [internal] load .dockerignore 0.0s => => transferring context: 2B 0.0s => [1/9] FROM docker.io/library/rust:1.72-slim-bookworm@sha256:ff798ceb500fa43c91db10db881066057fefd36e16d531e7b1ed228ab22 0.0s => [internal] load build context 0.3s => => transferring context: 1.06MB 0.3s => CACHED [2/9] RUN apt-get update && apt-get upgrade -y && apt-get install -y libssl-dev pkg-config protobuf-compiler 0.0s => CACHED [3/9] WORKDIR /usr/src/explorer 0.0s => CACHED [4/9] COPY Cargo.toml Cargo.lock ./ 0.0s => CACHED [5/9] COPY web/explorer /usr/src/explorer/web/explorer 0.0s => [6/9] RUN ls -R /usr/src/explorer/web/explorer/explorer-exe 0.2s => [7/9] WORKDIR /usr/src/explorer/web/explorer/explorer-exe 0.0s => [8/9] RUN mv config.dist.toml config.toml 0.1s => ERROR [9/9] RUN cargo build --release 0.2s ------ > [9/9] RUN cargo build --release:

0.180 error: failed to load manifest for workspace member /usr/src/explorer/chronik/abc-rust-error
0.180
0.180 Caused by:
0.180 failed to read /usr/src/explorer/chronik/abc-rust-error/Cargo.toml
0.180
0.180 Caused by:

0.180 No such file or directory (os error 2)

explorer.Dockerfile:26

24 |
25 |     # Build the project
26 | >>> RUN cargo build --release

ERROR: failed to solve: process "/bin/sh -c cargo build --release" did not complete successfully: exit code: 101
(myenv) ➜ bitcoin-abc git:(docker_fix) ✗ docker build -f explorer.Dockerfile -t my-explorer-image .`

Removed the --locked flag from explorer.Dockerfile and build-configurations.yml. By having --locked in the build-explorer configuration but not in the Dockerfile, we would create a mismatch between our local and CI/CD environments.

Test Plan: cargo check docker build -f explorer.Dockerfile -t my-explorer-something . ./contrib/teamcity/build-configurations.py build-explorer

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Subscribers: Fabien, redball4az

Differential Revision: https://reviews.bitcoinabc.org/D17352