Datatype deduplication 1: remove polars (#4880)

All the grunt work left to get rid of polars.

- Remove all helpers and APIs built specifically for polars'
`DataFrame`.
- Refactor tests that rely on dataframe joins to not require join
semantics in the first place (`re_data_store` has no knowledge of those
anyway).
- The one test that does require join semantics has moved over to
`re_query`, where join semantics belong.
- All `polars-*` dep have been removed.

Don't look at the commit log as it makes no sense: i changed strategies
a bunch of times on the way.

---

- Part of #4789
- DNR: requires #4856

---

Part of the tiny datatype deduplication PR series:
- #4880
- #4883

Cargo.toml

@@ -173,9 +173,6 @@ paste = "1.0"
 pathdiff = "0.2"
 pico-args = "0.5"
 ply-rs = { version = "0.1", default-features = false }
-polars-core = "0.29"
-polars-lazy = "0.29"
-polars-ops = "0.29"
 poll-promise = "0.3"
 pollster = "0.3"
 prettyplease = "0.2"

crates/re_data_store/Cargo.toml

@@ -22,16 +22,13 @@ default = []
 ## Enables `parking_lot`'s deadlock detection background thread.
 deadlock_detection = ["parking_lot/deadlock_detection"]
 
-## Integration with `polars`, to efficiently use the datastore with dataframes.
-polars = ["dep:polars-core", "dep:polars-ops"]
-
 
 [dependencies]
 # Rerun dependencies:
 re_error.workspace = true
 re_format = { workspace = true, features = ["arrow"] }
 re_log_types.workspace = true
-re_log.workspace = true
+re_log = { workspace = true, features = ["setup"] }
 re_tracing.workspace = true
 re_types_core.workspace = true
 
@@ -48,38 +45,13 @@ smallvec.workspace = true
 thiserror.workspace = true
 web-time.workspace = true
 
-# Optional dependencies:
-polars-core = { workspace = true, optional = true, features = [
-  "diagonal_concat",
-  "dtype-date",
-  "dtype-datetime",
-  "dtype-time",
-  "dtype-struct",
-  "sort_multiple",
-] }
-polars-ops = { workspace = true, optional = true, features = [
-  "dtype-date",
-  "dtype-datetime",
-  "dtype-time",
-  "dtype-struct",
-] }
-
 
 [dev-dependencies]
 re_types = { workspace = true, features = ["datagen", "testing"] }
 
 anyhow.workspace = true
 criterion.workspace = true
 mimalloc.workspace = true
-polars-core = { workspace = true, features = [
-  "diagonal_concat",
-  "dtype-date",
-  "dtype-datetime",
-  "dtype-struct",
-  "dtype-time",
-  "fmt",
-  "sort_multiple",
-] }
 rand.workspace = true
 similar-asserts.workspace = true
 tinyvec.workspace = true
@@ -88,27 +60,6 @@ tinyvec.workspace = true
 bench = false
 
 
-[[example]]
-name = "dump_dataframe"
-path = "examples/dump_dataframe.rs"
-required-features = ["polars"]
-
-[[example]]
-name = "latest_component"
-path = "examples/latest_component.rs"
-required-features = ["polars"]
-
-[[example]]
-name = "latest_components"
-path = "examples/latest_components.rs"
-required-features = ["polars"]
-
-[[example]]
-name = "range_components"
-path = "examples/range_components.rs"
-required-features = ["polars"]
-
-
 [[bench]]
 name = "arrow2"
 harness = false